Wavelength Dependence of the Absorption of Black Carbon Particles: Predictions and Results from the TARFOX Experiment and Implications for the Aerosol Single Scattering Albedo

Bergström, R. W.; Russell, Philip B.; Hignett, P.

doi:10.1175/1520-0469(2002)059<0567:wdotao>2.0.co;2

Cited by 360 publications

(344 citation statements)

References 54 publications

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“…In this study, SDE are defined as time periods that exhibit negative α SSA for more than 3 h. Log-log plots of daily means of a) the absorption coefficient and b) the single g albedo as a function of the wavelength for (black square) the day before the SDE 1), for (asterisk and star) SDE days (7-8.5.2001), and for (black circle) a stable day SDE ( 11.5.2001). The possible identification of mineral dust events by α SSA values was conceived using theoretical considerations (Bergstrom et al, 2002). The absorption coefficient measured using the integrating sandwich method during the Tropical Aerosol Radiative Forcing Observational Experiment (TARFOX) at the eastern coast of the United State shows an approximate λ −1 variation between 0.4 and 1.0 µm, but with a quicker decrease between 0.4 and 0.6 µm and a leveling off at longer wavelengths.…”

Section: Resultsmentioning

confidence: 77%

Saharan dust events at the Jungfraujoch: detection by wavelength dependence of the single scattering albedo and first climatology analysis

et al. 2004

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Abstract. Scattering and absorption coefficients have been measured continuously at several wavelengths since March 2001 at the high altitude site Jungfraujoch (3580 m a.s.l.). From these data, the wavelength dependences of the Angström exponent and particularly of the single scattering albedo are determined. While the exponent of the single scattering albedo usually increases with wavelength, it decreases with wavelength during Saharan dust events (SDE) due to the greater size of the mineral aerosol particles and their different chemical composition. This change in the sign of the single scattering exponent turns out to be a sensitive means for detecting Saharan dust events. The occurrence of SDE detected by this new method was confirmed by visual inspection of filter colors and by studying long-range backtrajectories. An examination of SDE over a 22-month period shows that SDE are more frequent during the March-June period as well as during October and November. The trajectory analysis indicated a mean traveling time of 96.5 h, with the most important source countries situated in the northern and north-western part of the Saharan desert. Most of the SDE do not lead to a detectable increase of the 48-h total suspended particulate matter (TSP) concentration at the Jungfraujoch. During Saharan dust events, the average contribution of this dust to hourly TSP at the Jungfraujoch is 16 µg/m 3 , which corresponds to an annual mean of 0.8 µg/m 3 or 24% of TSP.

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Section: Resultsmentioning

confidence: 77%

Saharan dust events at the Jungfraujoch: detection by wavelength dependence of the single scattering albedo and first climatology analysis

et al. 2004

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“…For reasonable particle size distributions and a LAC refractive index of m=1.55-0.5i, the theoretical values ofÅ typically varies between 0.2 and 1.2. Measurements confirm thatÅ abs values are close to 1 in aerosols in which pure C soot dominates the LAC, as has been shown by several authors for motor vehicle emissions and urban aerosols by in-situ measurements (Rosen et al, 1978;Horvath, 1997;Bergstrom et al, 2002;Schnaiter et al, 2003;Lawless et al, 2004;Bond and Bergstrom, 2006) and inversion of remote sensing data (Dubovik et al, 1998;Bergstrom et al, 2003). When absorption is stronger at shorter wavelengths, i.e., the particles appear brownish or yellow,Å will be significantly greater than unity.…”

Section: Wavelength Dependence Of Absorption and Its Possible Effect mentioning

confidence: 99%

Black carbon or brown carbon? The nature of light-absorbing carbonaceous aerosols

Andreae

Gelencsér²

2006

Atmos. Chem. Phys.

1,726

1,033

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Abstract. Although the definition and measurement techniques for atmospheric "black carbon" ("BC") or "elemental carbon'' ("EC") have long been subjects of scientific controversy, the recent discovery of light-absorbing carbon that is not black ("brown carbon, Cbrown") makes it imperative to reassess and redefine the components that make up light-absorbing carbonaceous matter (LAC) in the atmosphere. Evidence for the atmospheric presence of Cbrown comes from (1) spectral aerosol light absorption measurements near specific combustion sources, (2) observations of spectral properties of water extracts of continental aerosol, (3) laboratory studies indicating the formation of light-absorbing organic matter in the atmosphere, and (4) indirectly from the chemical analogy of aerosol species to colored natural humic substances. We show that brown carbon may severely bias measurements of "BC" and "EC" over vast parts of the troposphere, especially those strongly polluted by biomass burning, where the mass concentration of Cbrown is high relative to that of soot carbon. Chemical measurements to determine "EC" are biased by the refractory nature of Cbrown as well as by complex matrix interferences. Optical measurements of "BC" suffer from a number of problems: (1) many of the presently used instruments introduce a substantial bias into the determination of aerosol light absorption, (2) there is no unique conversion factor between light absorption and "EC" or "BC" concentration in ambient aerosols, and (3) the difference in spectral properties between the different types of LAC, as well as the chemical complexity of Cbrown, lead to several conceptual as well as practical complications. We also suggest that due to the sharply increasing absorption of Cbrown towards the UV, single-wavelength light absorption measurements may not be adequate for the assessment of absorption of solar radiation in the troposphere. We discuss the possible consequences of these effects for our understanding of tropospheric processes, including their influence on UV-irradiance, atmospheric photochemistry and radiative transfer in clouds.

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“…Thus, co-located measurements from January The Absorption Ångström Exponent (AAE) describes the wavelength dependency of the absorption coefficient and it can give information about the predominant aerosol type or source (e.g., Cazorla et al, 2013). In this sense, BC follows a λ -1 spectral dependency, yielding an AAE equal to 1 (Bergstrom et al, 2002), and organic carbon and mineral dust have a higher contribution to absorption in the ultraviolet (UV) and blue spectral regions yielding an AAE greater than 1 (Kirchstetter et al, 2004;Valenzuela et al, 2015). AAE has been calculated from the measured absorption coefficients, σap(λ), using Equation 4 for the wavelength pairs 370-520 nm and 370-950 nm.…”

Section: Aerosol Absorption Measurementsmentioning

confidence: 99%

Spatial and temporal variability of carbonaceous aerosols: Assessing the impact of biomass burning in the urban environment

Titos

Águila

Cazorla

et al. 2017

Science of The Total Environment

129

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Biomass burning (BB) is a significant source of atmospheric particles in many parts of the world. Whereas many studies have demonstrated the importance of BB emissions in central and northern Europe, especially in rural areas, its impact in urban air quality of southern European countries has been sparsely investigated. In this study, highly time resolved multi-wavelength absorption coefficients together with levoglucosan (BB tracer) mass concentrations were combined to apportion carbonaceous aerosol sources. TheAethalometer model takes advantage of the different spectral behaviour of BB and fossil fuel (FF) combustion aerosols. The model was found to be more sensitive to the assumed value of the aerosol Ångström exponent (AAE) for FF (AAEff) than to the AAE for BB (AAEbb). As result of various sensitivity tests the model was optimized with AAEff = 1.1 and AAEbb = 2. The Aethalometer model and levoglucosan tracer estimates were in good agreement. The Aethalometer model was further applied to data from three sites in Granada urban area to evaluate the spatial variation of CMff and CMbb (carbonaceous matter from FF or BB origin, respectively) concentrations within the city. The results showed that CMbb was lower in the city centre while it has an unexpected profound impact on the CM levels measured in the suburbs (about 40%). Analysis of BB tracers with respect to wind speed suggested that BB was dominated by sources outside the city, to the west in a rural area. Distinguishing whether it corresponds to agricultural waste burning or with biomass burning for domestic heating was not possible. This study also shows that although traffic restrictions measures contribute to reduce carbonaceous concentrations, the extent of the reduction is very local. Other sources such as BB, which can contribute to CM as much as traffic emissions, should be targeted to reduce air pollution.

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Wavelength Dependence of the Absorption of Black Carbon Particles: Predictions and Results from the TARFOX Experiment and Implications for the Aerosol Single Scattering Albedo

Cited by 360 publications

References 54 publications

Saharan dust events at the Jungfraujoch: detection by wavelength dependence of the single scattering albedo and first climatology analysis

Saharan dust events at the Jungfraujoch: detection by wavelength dependence of the single scattering albedo and first climatology analysis

Black carbon or brown carbon? The nature of light-absorbing carbonaceous aerosols

Spatial and temporal variability of carbonaceous aerosols: Assessing the impact of biomass burning in the urban environment

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