The atmospheric lifetime of black carbon

Cape, J. N.; Coyle, Mhairi; Dumitrean, P.

doi:10.1016/j.atmosenv.2012.05.030

Cited by 137 publications

(90 citation statements)

References 44 publications

(43 reference statements)

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“…For instance, estimating the lifetime by dividing the aerosol burden with its emission rate -a common definition of lifetime used by global aerosol modelers -results in a BC lifetime of 9 days. This is quite comparable to lifetime values reported for BC in the literature, though perhaps still somewhat longer than in most models (Samset et al, 2014;Cape et al, 2012;Ogren and Charlson, 1983).…”

Section: Discussionsupporting

confidence: 77%

A new aerosol wet removal scheme for the Lagrangian particle model FLEXPART v10

et al. 2017

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Abstract. A new, more physically based wet removal scheme for aerosols has been implemented in the Lagrangian particle dispersion model FLEXPART. It uses three-dimensional cloud water fields from the European Centre for MediumRange Weather Forecasts (ECMWF) to determine cloud extent and distinguishes between in-cloud and below-cloud scavenging. The new in-cloud nucleation scavenging depends on cloud water phase (liquid, ice or mixed-phase), based on the aerosol's prescribed efficiency to serve as ice crystal nuclei and liquid water nuclei, respectively. The impaction scavenging scheme now parameterizes below-cloud removal as a function of aerosol particle size and precipitation type (snow or rain) and intensity.Sensitivity tests with the new scavenging scheme and comparisons with observational data were conducted for three distinct types of primary aerosols, which pose different challenges for modeling wet scavenging due to their differences in solubility, volatility and size distribution: (1) 137 Cs released during the Fukushima nuclear accident attached mainly to highly soluble sulphate aerosol particles, (2) black carbon (BC) aerosol particles, and (3) mineral dust. Calculated e-folding lifetimes of accumulation mode aerosols for these three aerosol types were 11.7, 16.0, and 31.6 days respectively, when well mixed in the atmosphere. These are longer lifetimes than those obtained by the previous removal schem, and, for mineral dust in particular, primarily result from very slow in-cloud removal, which globally is the primary removal mechanism for these accumulation mode particles.Calculated e-folding lifetimes in FLEXPART also have a strong size dependence, with the longest lifetimes found for the accumulation-mode aerosols. For example, for dust particles emitted at the surface the lifetimes were 13.8 days for particles with 1 µm diameter and a few hours for 10 µm particles. A strong size dependence in below-cloud scavenging, combined with increased dry removal, is the primary reason for the shorter lifetimes of the larger particles. The most frequent removal is in-cloud scavenging (85 % of all scavenging events) but it occurs primarily in the free troposphere, while below-cloud removal is more frequent below 1000 m (52 % of all events) and can be important for the initial fate of species emitted at the surface, such as those examined here.For assumed realistic in-cloud removal efficiencies, both BC and sulphate have a slight overestimation of observed atmospheric concentrations (a factor of 1.6 and 1.2 respectively). However, this overestimation is largest close to the sources and thus appears more related to overestimated emissions rather than underestimated removal. The new aerosol wet removal scheme of FLEXPART incorporates more realistic information about clouds and aerosol properties and it compares better with both observed lifetimes and concentration than the old scheme.

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Section: Discussionsupporting

confidence: 77%

A new aerosol wet removal scheme for the Lagrangian particle model FLEXPART v10

et al. 2017

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“…The hydrophilic state of BC affects cloud scavenging and wet deposition, which remains the greatest source of uncertainty in models Vignati et al, 2010b). As a result, the lifetime of BC has been estimated to range from a few days up to 2 weeks (Cape et al, 2012;Ramanathan and Carmichael, 2008). Koch et al (2009) have investigated the performance of a model ensemble (AeroCom) in predicting atmospheric BC concentrations and concluded that the simulations tend to underpredict BC concentrations only in some outflow regions, especially in Asia, but overestimate the concentrations in remote areas, especially at high altitudes.…”

Section: Light-absorbing Carbonmentioning

confidence: 99%

Particulate matter, air quality and climate: lessons learned and future needs

et al. 2015

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Abstract. The literature on atmospheric particulate matter (PM), or atmospheric aerosol, has increased enormously over the last 2 decades and amounts now to some 1500-2000 papers per year in the refereed literature. This is in part due to the enormous advances in measurement technologies, which have allowed for an increasingly accurate understanding of the chemical composition and of the physical properties of atmospheric particles and of their processes in the atmosphere. The growing scientific interest in atmospheric aerosol particles is due to their high importance for environmental policy. In fact, particulate matter constitutes one of the most challenging problems both for air quality and for climate change policies. In this context, this paper reviews the most recent results within the atmospheric aerosol sciences and the policy needs, which have driven much of the increase in monitoring and mechanistic research over the last 2 decades.The synthesis reveals many new processes and developments in the science underpinning climate-aerosol interactions and effects of PM on human health and the environment. However, while airborne particulate matter is responsible for globally important influences on premature human mortality, we still do not know the relative importance of the different chemical components of PM for these effects. Likewise, the magnitude of the overall effects of PM on climate remains highly uncertain. Despite the uncertainty there are many things that could be done to mitigate local and global problems of atmospheric PM. Recent analyses have shown that reducing black carbon (BC) emissions, using known control measures, would reduce global warming and delay the time when anthropogenic effects on global temperature would exceed 2 • C. Likewise, cost-effective control measures on ammonia, an important agricultural precursor gas for secondary inorganic aerosols (SIA), would reduce regional eutrophication and PM concentrations in large areas of Europe, China and the USA. Thus, there is much that could be done to reduce the effects of atmospheric PM on the climate and the health of the environment and the human population.A prioritized list of actions to mitigate the full range of effects of PM is currently undeliverable due to shortcomings in the knowledge of aerosol science; among the shortcomings, the roles of PM in global climate and the relative roles of Published by Copernicus Publications on behalf of the European Geosciences Union. 8218S. Fuzzi et al.: Particulate matter, air quality and climate different PM precursor sources and their response to climate and land use change over the remaining decades of this century are prominent. In any case, the evidence from this paper strongly advocates for an integrated approach to air quality and climate policies.

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“…Both PM 2.5 and BC have been classified as mesoscale air pollutants that can travel tens to hundreds of kilometers (Krudysz et al, 2008;Wang et al, 2011). This is because their atmospheric lifetime is fairly long so that they can be transported and dispersed within a large region (Cape et al, 2012;Chen et al, 2013). When the atmospheric conditions are stagnant, PM 2.5 and BC concentrations may also increase if local emission sources such as traffic exist.…”

Section: Ufp Pm 25 and Bc Concentrationsmentioning

confidence: 99%

Characterization of Ultrafine Particles and Other Traffic Related Pollutants near Roadways in Beijing

Xie

2015

Aerosol Air Qual. Res.

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Developing countries, such as China, are facing serious air pollution issues due to fast economic development. In this study, traffic related air pollutants, including number concentration of ultrafine particles (UFPs, diameter < 100 nm), mass concentrations of PM 2.5 and black carbon (BC) were measured near the Peking University (PKU) campus in Beijing in December 2011. Data were collected concurrently at a roadway site and on PKU campus. Meteorological data were collected at approximately 40 meters northeast from the roadway sampling site. The traffic density was determined from recorded video footage. Roadside UFP and PM 2.5 concentrations were not significantly higher than on campus. A statistically significant Pearson's correlation of 0.75 was found between BC and PM 2.5 mass concentrations. No apparent correlation was found between wind speed and UFP number concentrations, but strong log-decay correlations were found between wind speed and PM 2.5 (R 2 = 0.80). There were three days during the measurements when both PM 2.5 mass concentrations and UFP number concentrations were higher at the campus site than at the roadway site. This suggests there were potential local emission sources on campus. Temporal profile of UFPs at the campus site peaked around lunch and dinner time, suggesting emissions from the surrounding restaurants and cafeteria that used Chinese-style cooking might have contributed to the observed PM 2.5 and UFP levels on campus.

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The atmospheric lifetime of black carbon

Cited by 137 publications

References 44 publications

A new aerosol wet removal scheme for the Lagrangian particle model FLEXPART v10

A new aerosol wet removal scheme for the Lagrangian particle model FLEXPART v10

Particulate matter, air quality and climate: lessons learned and future needs

Characterization of Ultrafine Particles and Other Traffic Related Pollutants near Roadways in Beijing

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