Cloud scavenging of anthropogenic refractory particles at a mountain site in North China

Liu, Lei; Zhang, Jian; Xu, Liang; Yuan, Qi; Huang, D.H.; Chen, Jianmin; Shi, Zongbo; Sun, Yele; Fu, Pingqing; Wang, Zifa; Zhang, Daizhou; Li, Weijun

doi:10.5194/acp-18-14681-2018

Cited by 29 publications

(21 citation statements)

References 57 publications

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“…Emitted at ground, these particles can be transported from the boundary layer as far as to the lowermost stratosphere (Ditas et al., ). When the vertical transport takes place in deep convective cloud systems, the soot particles can be scavenged by cloud droplets (Ding et al., ; Liu et al., ) or can activate into supercooled liquid cloud droplets at subzero temperatures (Andreae et al., ), similar to conditions of our MPC processing. Often large smoke aerosols are co‐emitted with large number concentrations of smaller carbonaceous particles.…”

Section: Atmospheric Implicationsmentioning

confidence: 97%

The Impact of Cloud Processing on the Ice Nucleation Abilities of Soot Particles at Cirrus Temperatures

et al. 2020

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Soot particles are generally considered to be poor ice nucleating particles. Involvement of soot in clouds and their release back into the atmosphere can form residual particles with altered cloud forming potential. The impact and extent of such different cloud processing scenarios on ice nucleation is, however, not well understood. In this work, we present the impact of cloud processing of soot aerosols on subsequent ice nucleation cycles at T≤233 K. Coupling of two continuous flow diffusion chambers allows the simulation of different cloud processing scenarios and investigation of subsequent ice nucleation activity of the processed particles. The processing scenarios presented here encompass contrail, cirrus, and mixed‐phase cloud processing, mimicking typical pathways that soot particles can be exposed to in the atmosphere. For all scenarios tested, the processed particles showed an enhanced ice active fraction for T<233 K. The relative humidity with respect to water for the ice nucleation onset was observed to be on average approximately 10% (relative humidity with respect to ice, RHi≈16%) lower for the cloud‐processed particles compared to the unprocessed soot for which ice nucleation was observed close to or at homogeneous freezing conditions of solution droplets. We attribute the enhanced ice nucleation abilities of the cloud‐processed soot to a pore condensation and freezing mechanism and have identified key parameters governing these changes. Enhanced ice nucleation abilities of soot in cirrus clouds can have significant impacts, given the importance of the atmospheric ice phase for precipitation formation and global climate.

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Section: Atmospheric Implicationsmentioning

confidence: 97%

The Impact of Cloud Processing on the Ice Nucleation Abilities of Soot Particles at Cirrus Temperatures

et al. 2020

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“…Size and mixing state are known to be crucial in influencing the lifetime of BC via nucleation scavenging [87,155]. Recent studies have described the size and mixing state of BC with other substances in cloud droplets with SPMS, transmission electron microscopy (TEM), or SP2 [8,11,39,40]. Furthermore, such studies were mostly performed in urban environment [156][157][158].…”

Section: More Field Measurements On the Direct Links Between Ses Of Bmentioning

confidence: 99%

“…The indirect effect refers to the change of microphysical and radiative properties of clouds and its lifetime by acting as cloud condensation nuclei (CCN) or ice nuclei (IN) [4][5][6][7]. BC is ubiquitous in fog/cloud droplets and ice crystals [8][9][10][11], but its ability to serve as CCN/IN remains ambiguous [12], representing a major uncertainty in its climate effect. In mixed-phase or ice cloud, BC may promote the occurrence of precipitation [13].…”

Section: Introductionmentioning

confidence: 99%

Recent Advances in Quantifying Wet Scavenging Efficiency of Black Carbon Aerosol

Yang

Lin

et al. 2019

Atmosphere

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Black carbon (BC) aerosol is of great importance not only for its strong potential in heating air and impacts on cloud, but also because of its hazards to human health. Wet deposition is regarded as the main sink of BC, constraining its lifetime and thus its impact on the environment and climate. However, substantial controversial and ambiguous issues in the wet scavenging processes of BC are apparent in current studies. Despite of its significance, there are only a small number of field studies that have investigated the incorporation of BC-containing particles into cloud droplets and influencing factors, in particular, the in-cloud scavenging, because it was simplicitly considered in many studies (as part of total wet scavenging). The mass scavenging efficiencies (MSEs) of BC were observed to be varied over the world, and the influencing factors were attributed to physical and chemical properties (e.g., size and chemical compositions) and meteorological conditions (cloud water content, temperature, etc.). In this review, we summarized the MSEs and potential factors that influence the in-cloud and below-cloud scavenging of BC. In general, MSEs of BC are lower at low-altitude regions (urban, suburban, and rural sites) and increase with the rising altitude, which serves as additional evidence that atmospheric aging plays an important role in the chemical modification of BC. Herein, higher altitude sites are more representative of free-tropospheric conditions, where BC is usually more aged. Despite of increasing knowledge of BC–cloud interaction, there are still challenges that need to be addressed to gain a better understanding of the wet scavenging of BC. We recommend that more comprehensive methods should be further estimated to obtain high time-resolved scavenging efficiency (SE) of BC, and to distinguish the impact of in-cloud and below-cloud scavenging on BC mass concentration, which is expected to be useful for constraining the gap between field observation and modeling simulation results.

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“…Even with similar O / C ratios, the molecular compositions of organics in aerosols and cloud water could be quite different; for example, the organosulfate hydrolysis and nitrogen-containing compound formation were observed more often in cloud water compared to at-mospheric particles, suggesting the significant role of cloud processing in changing the chemical properties of aerosols (Boone et al, 2015). In addition to the in-cloud sulfate formation (Meng and Seinfeld, 1994), the in-cloud organic formation is also likely to add substantial mass to dropletmode particles (Ervens et al, 2011). For example, maximum droplet-mode organics and a shift in particle mass size distribution were observed in simulated cloud events (Brégonzio-Rozier et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Chemical characteristics of cloud water and the impacts on aerosol properties at a subtropical mountain site in Hong Kong SAR

Wang

et al. 2020

Atmos. Chem. Phys.

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Abstract. To investigate the cloud water chemistry and the effects of cloud processing on aerosol properties, comprehensive field observations of cloud water, aerosols, and gas-phase species were conducted at a mountaintop site in Hong Kong SAR in October and November 2016. The chemical composition of cloud water including water-soluble ions, dissolved organic matter (DOM), carbonyl compounds (refer to aldehydes and acetone), carboxylic acids, and trace metals was quantified. The measured cloud water was very acidic with a mean pH of 3.63, as the ammonium (174 µeq L−1) was insufficient for neutralizing the dominant sulfate (231 µeq L−1) and nitrate (160 µeq L−1). Substantial DOM (9.3 mgC L−1) was found in cloud water, with carbonyl compounds and carboxylic acids accounting for 18 % and 6 % in carbon molar concentrations, respectively. Different from previous observations, concentrations of methylglyoxal (19.1 µM; µM is equal to µmol L−1) and glyoxal (6.72 µM) were higher than that of formaldehyde (1.59 µM). The partitioning of carbonyls between cloud water and the gas phase was also investigated. The measured aqueous fractions of dicarbonyls were comparable to the theoretical estimations, while significant aqueous-phase supersaturation was found for less soluble monocarbonyls. Both organics and sulfate were significantly produced in cloud water, and the aqueous formation of organics was more enhanced by photochemistry and under less acidic conditions. Moreover, elevated sulfate and organics were measured in the cloud-processed aerosols, and they were expected to contribute largely to the increase in droplet-mode aerosol mass fraction. This study demonstrates the significant role of clouds in altering the chemical compositions and physical properties of aerosols via scavenging and aqueous chemical processing, providing valuable information about gas–cloud–aerosol interactions in subtropical and coastal regions.

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Cloud scavenging of anthropogenic refractory particles at a mountain site in North China

Cited by 29 publications

References 57 publications

The Impact of Cloud Processing on the Ice Nucleation Abilities of Soot Particles at Cirrus Temperatures

The Impact of Cloud Processing on the Ice Nucleation Abilities of Soot Particles at Cirrus Temperatures

Recent Advances in Quantifying Wet Scavenging Efficiency of Black Carbon Aerosol

Chemical characteristics of cloud water and the impacts on aerosol properties at a subtropical mountain site in Hong Kong SAR

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