Phase partitioning for different aerosol species in fog

Hallberg, A.; OGREN, J. A.; Noone, Kevin J.; Heintzenberg, Jost; Berner, A.; SOLLY, I.; Kruisz, C.; REISCHL, G.; Fuzzi, S.; Facchini, M. C.; Hansson, H.‐C.; WIEDENSOHLER, A.; SVENNINGSSON, I. B.

doi:10.1034/j.1600-0889.1992.t01-2-00008.x

Cited by 38 publications

(29 citation statements)

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“…Citations Environment Average Scavenged BC Mass Fraction Po Valley, Italy [24] Urban 0.06 Kleiner Feldberg, Germany [25] Rural 0.15 Puy de Dome, France [26] Mid altitude (1465 m) 0.33 Mt. Sonnblick, Austria [27] Mid altitude (3106 m) 0.45 Rax, Austria [22] Mid altitude (1644 m) 0.54 Great Dun Fell, UK [28] Rural-Coastal 0.57 Jungfraujoch, Switzerland [23] High altitude (3850 m) 0.61 Mt.…”

Section: Sampling Sitementioning

confidence: 99%

Quantifying Impacts of Aerosol Mixing State on Nucleation-Scavenging of Black Carbon Aerosol Particles

2018

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Abstract:Recent observational studies suggest that nucleation-scavenging is the principal path to removing black carbon-containing aerosol from the atmosphere, thus affecting black carbon's lifetime and radiative forcing. Modeling the process of nucleation-scavenging is challenging, since black carbon (BC) forms complex internal mixtures with other aerosol species. Here, we examined the impacts of black carbon mixing state on nucleation scavenging using the particle-resolved aerosol model PartMC-MOSAIC. This modeling approach has the unique advantage that complex aerosol mixing states can be represented on a per-particle level. For a scenario library that comprised hundreds of diverse aerosol populations, we quantified nucleation-scavenged BC mass fractions. Consistent with measurements, these vary widely, depending on the amount of BC, the amount of coating and coating material, as well as the environmental supersaturation. We quantified the error in the nucleation-scavenged black carbon mass fraction introduced when assuming an internally mixed distribution, and determined its bounds depending on environmental supersaturation and on the aerosol mixing state index χ. For a given χ value, the error decreased at higher supersaturations. For more externally mixed populations (χ < 20%), the nucleation-scavenged BC mass fraction could be overestimated by more than 1000% at supersaturations of 0.1%, while for more internally mixed populations (χ > 75%), the error was below 100% for the range of supersaturations (from 0.02% to 1%) investigated here. Accounting for black carbon mixing state and knowledge of the supersaturation of the environment are crucial when determining the amount of black carbon that can be incorporated into clouds.

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Section: Sampling Sitementioning

confidence: 99%

Quantifying Impacts of Aerosol Mixing State on Nucleation-Scavenging of Black Carbon Aerosol Particles

2018

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“…The hygroscopicity and size of BC-containing particles are determining factors for r scav (Sellegri et al, 2003;Hallberg et al, 1992Hallberg et al, , 1995. Internal mixing with soluble inorganic species enhances the r scav for aged BC particles (Sellegri et al, 2003).…”

Section: Wegener-bergeron-findeisen (Wbf) Process In Mixed-phase Cloudsmentioning

confidence: 99%

Factors controlling black carbon distribution in the Arctic

Liu¹,

Li²,

et al. 2017

Atmos. Chem. Phys.

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Abstract. We investigate the sensitivity of black carbon (BC) in the Arctic, including BC concentration in snow (BC snow , ng g −1 ) and surface air (BC air , ng m −3 ), as well as emissions, dry deposition, and wet scavenging using the global threedimensional (3-D) chemical transport model (CTM) GEOSChem. We find that the model underestimates BC snow in the Arctic by 40 % on average (median = 11.8 ng g −1 ). Natural gas flaring substantially increases total BC emissions in the Arctic (by ∼ 70 %). The flaring emissions lead to up to 49 % increases (0.1-8.5 ng g −1 ) in Arctic BC snow , dramatically improving model comparison with observations (50 % reduction in discrepancy) near flaring source regions (the western side of the extreme north of Russia). Ample observations suggest that BC dry deposition velocities over snow and ice in current CTMs (0.03 cm s −1 in the GEOS-Chem) are too small. We apply the resistance-in-series method to compute a dry deposition velocity (v d ) that varies with local meteorological and surface conditions. The resulting velocity is significantly larger and varies by a factor of 8 in the Arctic (0.03-0.24 cm s −1 ), which increases the fraction of dry to total BC deposition (16 to 25 %) yet leaves the total BC deposition and BC snow in the Arctic unchanged. This is largely explained by the offsetting higher dry and lower wet deposition fluxes. Additionally, we account for the effect of the Wegener-Bergeron-Findeisen (WBF) process in mixed-phase clouds, which releases BC particles from condensed phases (water drops and ice crystals) back to the interstitial air and thereby substantially reduces the scavenging efficiency of clouds for BC (by 43-76 % in the Arctic). The resulting BC snow is up to 80 % higher, BC loading is considerably larger (from 0.25 to 0.43 mg m −2 ), and BC lifetime is markedly prolonged (from 9 to 16 days) in the Arctic. Overall, flaring emissions increase BC air in the Arctic (by ∼ 20 ng m −3 ), the updated v d more than halves BC air (by ∼ 20 ng m −3 ), and the WBF effect increases BC air by 25-70 % during winter and early spring. The resulting model simulation of BC snow is substantially improved (within 10 % of the observations) and the discrepancies of BC air are much smaller during the snow season at Barrow, Alert, and Summit (from −67-−47 % to −46-3 %). Our results point toward an urgent need for better characterization of flaring emissions of BC (e.g., the emission factors, temporal, and spatial distribution), extensive measurements of both the dry deposition of BC over snow and ice, and the scavenging efficiency of BC in mixed-phase clouds. In addition, we find that the poorly constrained precipitation in the Arctic may introduce large uncertainties in estimating BC snow . Doubling precipitation introduces a positive bias approximately as large as the overall effects of flaring emissions and the WBF effect; halving precipitation produces a similarly large negative bias.

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“…For aromatic compounds the same ratio was 0.6, intermediate between nonpolar alcohols and slightly polar monocarboxylic acids for which about 40% of the molecules were measured in cloud water. Hallberg et al (1992) studied the unscavenged fraction of aerosol in fog droplets. The fraction of elemental carbon was found to be significantly more abundant than for sulfate.…”

Section: Wet Scavenging Of Organic Aerosolsmentioning

confidence: 99%

Organic aerosol and global climate modelling: a review

et al. 2005

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Abstract. The present paper reviews existing knowledge with regard to Organic Aerosol (OA) of importance for global climate modelling and defines critical gaps needed to reduce the involved uncertainties. All pieces required for the representation of OA in a global climate model are sketched out with special attention to Secondary Organic Aerosol (SOA): The emission estimates of primary carbonaceous particles and SOA precursor gases are summarized. The up-to-date understanding of the chemical formation and transformation of condensable organic material is outlined. Knowledge on the hygroscopicity of OA and measurements of optical properties of the organic aerosol constituents are summarized. The mechanisms of interactions of OA with clouds and dry and wet removal processes parameterisations in global models are outlined. This information is synthesized to provide a continuous analysis of the flow from the emitted material to the atmosphere up to the point of the climate impact of the produced organic aerosol. The sources of uncertainties at each step of this process are highlighted as areas that require further studies.

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Phase partitioning for different aerosol species in fog

Cited by 38 publications

References 0 publications

Quantifying Impacts of Aerosol Mixing State on Nucleation-Scavenging of Black Carbon Aerosol Particles

Quantifying Impacts of Aerosol Mixing State on Nucleation-Scavenging of Black Carbon Aerosol Particles

Factors controlling black carbon distribution in the Arctic

Organic aerosol and global climate modelling: a review

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