Precipitation removal of ultrafine aerosol particles from the atmospheric boundary layer

Andronache, C.

doi:10.1029/2003jd004050

Cited by 24 publications

(15 citation statements)

References 62 publications

(82 reference statements)

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“…through chemical reactions taking place in cloud water. Furthermore, precipitating clouds are an effective removal mechanism of atmospheric particles (Andronache, 2004).…”

Section: Introductionmentioning

confidence: 99%

CCN activation and cloud processing in sectional aerosol models with low size resolution

et al. 2005

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Abstract.We investigate the influence of low size resolution, typical to sectional aerosol models in large scale applications, on cloud droplet activation and cloud processing of aerosol particles. A simplified cloud model with five approaches to determine the fraction of activated particles is compared with a detailed reference model under different atmospheric conditions. In general, activation approaches which assume a distribution profile within the critical model size sections predict the cloud droplet concentration most accurately under clean and moderately polluted conditions. In such cases, the deviation from the reference simulations is below 15% except for very low updraft velocities. In highly polluted cases, the concentration of cloud droplets is significantly overestimated due to the inability of the simplified model to account for the kinetic limitations of the droplet growth. Of the profiles examined, taking into account the local shape of the particle size distribution is the most accurate although in most cases the shape of the profile has little relevance. While the low resolution cloud model cannot reproduce the details of the out-of-the-cloud aerosol size distribution, it captures well the amount of sulphate produced in aqueous-phase reactions as well as the distribution of the sulphate between the cloud droplets. Overall, the simplified cloud model with low size resolution performs well for clean and moderately polluted regions that cover most of the Earth's surface and is therefore suitable for large scale models. It can, however, show uncertainties in areas with strong pollution from anthropogenic sources.

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“…through chemical reactions taking place in cloud water. Furthermore, precipitating clouds are an effective removal mechanism of atmospheric particles (Andronache, 2004).…”

Section: Introductionmentioning

confidence: 99%

CCN activation and cloud processing in sectional aerosol models with low size resolution

et al. 2005

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“…High temporal and spatial homogeneity imply a long life-time of these particles, which can be explained by the low aerosol dynamical progression rates of accumulation mode particles, including coagulation and sedimentation (Hinds, 1999;Seinfeld and Pandis, 2006). As a consequence, wet deposition tends to be the critical limiting factor for the life-time of continental accumulation mode particles (Andronache, 2004). …”

Section: Statistical Factors In the Accumulation Mode Rangementioning

confidence: 99%

Spatio-temporal variability and principal components of the particle number size distribution in an urban atmosphere

et al. 2009

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Abstract.A correct description of fine (diameter <1 µm) and ultrafine (<0.1 µm) aerosol particles in urban areas is of interest for particle exposure assessment but also basic atmospheric research. We examined the spatio-temporal variability of atmospheric aerosol particles (size range 3-800 nm) using concurrent number size distribution measurements at a maximum of eight observation sites in and around Leipzig, a city in Central Europe. Two main experiments were conducted with different time span and number of observation sites (2 years at 3 sites; 1 month at 8 sites). A general observation was that the particle number size distribution varied in time and space in a complex fashion as a result of interaction between local and far-range sources, and the meteorological conditions. To identify statistically independent factors in the urban aerosol, different runs of principal component (PC) analysis were conducted encompassing aerosol, gas phase, and meteorological parameters from the multiple sites. Several of the resulting PCs, outstanding with respect to their temporal persistence and spatial coverage, could be associated with aerosol particle modes: a first accumulation mode ("droplet mode", 300-800 nm), considered to be the result of liquid phase processes and far-range transport; a second accumulation mode (centered around diameters 90-250 nm), considered to result from primary emissions as well as aging through condensation and coagulation; an Aitken mode (30-200 nm) linked to urban traffic emissions in addition to an urban and a rural Aitken mode; a nucleation mode (5-20 nm) linked to urban traffic emissions; nucleation modes Correspondence to: W. Birmili (birmili@tropos.de) (3-20 nm) linked to photochemically induced particle formation; an aged nucleation mode (10-50 nm). Additional PCs represented only local sources at a single site, or infrequent phenomena. In summary, the analysis of size distributions of high time and size resolution yielded a surprising wealth of statistical aerosol components occurring in the urban atmosphere over one single city. A paradigm on the behaviour of sub-µm urban aerosol particles is proposed, with recommendations how to efficiently monitor individual sub-fractions across an entire city.

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“…-Cloud-aerosol interactions: Ultrafine aerosol particles are removed efficiently by precipitation (Andronache, 2004) before growing to cloud condensation nuclei. However, an increase in aerosol concentrations reduces drizzle via the second indirect aerosol effect and thus the removal of ultrafine particles.…”

Section: Uncertaintiesmentioning

confidence: 99%

Aerosol nucleation over oceans and the role of galactic cosmic rays

et al. 2006

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Abstract. We investigate formation of sulfate aerosol in the marine troposphere from neutral and charged nucleation of H 2 SO 4 and H 2 O. A box model of neutral and charged aerosol processes is run on a grid covering the oceans. Input data are taken from a model of galactic cosmic rays in the atmosphere, and from global chemistry and transport models. We find a weak aerosol production over the tropical oceans in the lower and middle troposphere, and a stronger production at higher latitudes, most notably downwind of industrial regions. The strongest aerosol production however occurs in the upper troposphere over areas with frequent convective activity, in particular in the tropics. This finding supports the proposition by which non-sea salt marine boundary layer aerosol in tropical regions does not form in situ, but nucleates in the upper troposphere from convectively lifted and cloud processed boundary layer air rich in aerosol precursor gases, from where it descends in subsiding air masses compensating convection. Convection of boundary layer air also appears to drive the formation of condensation nuclei in the tropical upper troposphere which maintains the stratospheric aerosol layer in the absence of volcanic activity. Neutral nucleation contributes only marginally to aerosol production in our simulations. This highlights the importance of other mechanisms, including charged binary and ternary, and neutral ternary nucleation for aerosol formation. Our analysis indicates that the variation of ionization by galactic cosmic rays over the decadal solar cycle does not entail a response in aerosol production and cloud cover via the second indirect aerosol effect that would explain observed variations in global cloud cover. We estimate that the variation in radiative forcing resulting from a response of clouds to the change in galactic cosmic ray ionization and subsequent aerosol production over the decadal solar cycle is smaller than the concurrent variation of total solar irradiance.

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Precipitation removal of ultrafine aerosol particles from the atmospheric boundary layer

Cited by 24 publications

References 62 publications

CCN activation and cloud processing in sectional aerosol models with low size resolution

CCN activation and cloud processing in sectional aerosol models with low size resolution

Spatio-temporal variability and principal components of the particle number size distribution in an urban atmosphere

Aerosol nucleation over oceans and the role of galactic cosmic rays

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