Changes in aerosol size- and phase distributions due to physical and chemical processes in fog

Noone, Kevin J.; Ogren, J. A.; HALLBERG, ANNELI; Heintzenberg, Jost; STROM, JOHAN; Hansson, Hans‐Christen; Svenningsson, Birgitta; Wiedensohler, Alfred; Fuzzi, S.; Facchini, M. C.; Arends, B. G.; BERNER, AXEL

doi:10.1034/j.1600-0889.1992.t01-4-00004.x

Cited by 52 publications

(37 citation statements)

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“…For the polluted case corresponding to 16-17 July 1997 we found that the majority of the residual particles measured in the Sc clouds with the CVI were larger than 0.1 ¹m in diameter. This is consistent with residual particle size distributions observed in polluted Sc clouds over the North Sea on 9 March 1997 and scavenging ef ciencies in polluted fogs over a continental area (Noone et al 1992). Furthermore, for all cases marked in bold and corresponding to the clean category shown in the table a linear correlation coef cient .r/ of 0.96 is obtained between N aer amp and SF Namp .…”

Section: (C) Observed Cloud Droplet Distributions In Sc and Cu Cloudssupporting

confidence: 86%

“…Glantz and Noone (2000) suggest that as the level of pollution increases in the layer in which clouds form, larger particles can become suf ciently abundant to account for the majority of the cloud droplets formed. For highly polluted conditions Noone et al (1992), using a CVI, observed AMP number-and volumescavenging fractions as low as 1-10% and 20-30%, respectively, in fogs. They also found that particles smaller than 0.3 ¹m diameter were not ef ciently scavenged in the polluted fogs.…”

Section: Introductionmentioning

confidence: 96%

“…For accumulation-mode particles (AMPs), activation is by far the predominant process in the incorporation of aerosols into cloud droplets, while for smaller particles other processes such as Brownian coagulation may also lead to some aerosol scavenging (Flossmann et al 1985;Noone et al 1992). The latter process is probably only signi cant in terms of changing the number concentration of interstitial Aitken nuclei.…”

Section: Introductionmentioning

confidence: 99%

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Scavenging efficiencies of aerosol particles in marine stratocumulus and cumulus clouds

Glantz¹,

Noone²,

Osborne³

2003

Quart J Royal Meteoro Soc

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SUMMARYScavenging ef ciencies of aerosol particles in marine stratocumulus and cumulus clouds obtained using Counter ow Virtual Impactors mounted on aircraft are presented as a function of pollution level. The greatest accumulation-mode particle number and mass-scavenging fractions were found for clean conditions, and are consistent with (but slightly lower than) previous studies. Vertical gradients in the concentrations of coarse-mode particles observed in shallow and decoupled marine boundary layers reduced the in uence of sea-salt particles, in terms of broadening the cloud droplet spectra and as a possible mechanism to oxidize SO 2 to non-sea-salt sulphate in the marine stratiform cloud layer. For supersaturations typical for marine stratocumulus clouds, particles smaller than 0.1 ¹m in diameter dominated the formation of cloud droplets for several of the cases analysed here. For larger supersaturations, in stratocumulus clouds inside an area of cumulus penetration, the concentration of residual particles smaller than 0.1 ¹m in diameter was nearly a factor of three higher than the accumulation-mode number. Poor correlation was found between accumulation-mode residual particle number and mass with cloud droplet number for the clean-condition category. This suggests that the particles determining the cloud droplet number populations in clean conditions and for polluted situations with relatively large updraughts were below the accumulation-mode size range. Additionally, it seems that the droplet numbers were insensitive to changes in the accumulation-mode mass for these conditions.

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Section: (C) Observed Cloud Droplet Distributions In Sc and Cu Cloudssupporting

confidence: 86%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Scavenging efficiencies of aerosol particles in marine stratocumulus and cumulus clouds

Glantz¹,

Noone²,

Osborne³

2003

Quart J Royal Meteoro Soc

Self Cite

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“…Several investigators (Tucker, 1989;Noone et al, 1991Noone et al, , 1992bOgren et al, 1992) have deployed miniaturized, landbased CVIs similar to the one discussed here. These have proven to be useful field instruments; however, they have yet to be carefully calibrated, especially with regard to the minimum cut size and the cut sharpness.…”

Section: Introductionmentioning

confidence: 99%

Calibration of a Counterflow Virtual Impactor at Aerodynamic Diameters from 1 to 15 μm

Anderson

Charlson

Covert

1993

Aerosol Science and Technology

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Unlike traditional virtual impactors, which suffer from a fixed level of small particle contamination in the large particle sample stream, the counterflow virtual impactor (CVI; Ogren et al., 1985) offers the potential for contamination-free sampling of large aerosol particles. Here we present the design and calibration of a CVI intended for studying aerosol effects on cloud microphysics. Such srudies require that a large and well-characterized fraction of total cloud droplet number be sampled and that the interstitial aerosol be excluded. The new CVI provides cut sizes (i.e., 50%

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“…The stable conditions lead to the trapping of pollutants and aerosol particles in the lower layers. This indicates that under the stable, cold and sub-saturated conditions (humidity greater than 80%), initiation of aerosol hydration (not full activation in fog droplets) as haze particles and, to a lesser extent, activation of aerosols in fog droplets 30,31 , might have occurred resulting in quasi-fog/haze conditions following the dense fog. These observations show the complexity of the role of aerosols, suggesting that different processes are at play during various phases of the fog event.…”

Section: Key Processes Involved During Fog Event: 21-25 January 2016mentioning

confidence: 99%

Winter Fog Experiment Over the Indo-Gangetic Plains of India

et al. 2017

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The objectives of the Winter Fog Experiment (WIFEX) over the Indo-Gangetic Plains of India are to develop better now-casting and forecasting of winter fog on various time-and spatial scales. Maximum fog occurrence over northwest India is about 48 days (visibility <1000 m) per year, and it occurs mostly during the December-February time-period. The physical and chemical characteristics of fog, meteorological factors responsible for its genesis, sustenance, intensity and dissipation are poorly understood. Improved understanding on the above aspects is required to develop reliable forecasting models and observational techniques for accurate prediction of the fog events. Extensive sets of comprehensive groundbased instrumentation were deployed at the Indira Gandhi International Airport, New Delhi. Major in situ sensors were deployed to measure surface micrometeorological conditions, radiation balance, turbulence, thermodynamical structure of the surface layer, fog droplet and aerosol microphysics, aerosol optical properties, and aerosol and fog water chemistry to describe the complete environmental conditions under which fog develops. In addition, Weather Forecasting Model coupled with chemistry is planned for fog prediction at a spatial resolution of 2 km. The present study provides an introductory overview of the winter fog field campaign with its unique instrumentation.

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Changes in aerosol size- and phase distributions due to physical and chemical processes in fog

Cited by 52 publications

References 0 publications

Scavenging efficiencies of aerosol particles in marine stratocumulus and cumulus clouds

Scavenging efficiencies of aerosol particles in marine stratocumulus and cumulus clouds

Calibration of a Counterflow Virtual Impactor at Aerodynamic Diameters from 1 to 15 μm

Winter Fog Experiment Over the Indo-Gangetic Plains of India

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