An Investigation of the Size-Supersaturation Relationship of Soluble Condensation Nuclei

Katz, U.; Kocmond, W. C.

doi:10.1175/1520-0469(1973)030<0160:aiotss>2.0.co;2

Cited by 21 publications

(9 citation statements)

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“…within the particle growth chamber), recent emphasis has been placed on accurate specification of this operationally-defined supersaturation. Seminal work on this problem was ambiguous showing either that the maximum supersaturation derived using chamber temperatures exceeded (Katz and Kocmond, 1973) or that it was consistent with the maximum supersaturation derived from a particle size sufficient for activation (Gerber et al, 1977;Alofs et al, 1979). Consistency in this context implies that measured temperatures, transformed to a maximum chamber supersaturation via a model of the temperature and vapour fields, is consistent with the chamber supersaturation derived by inputting the minimum dry size necessary for activation into Köhler theory.…”

Section: Ccn Measurementmentioning

confidence: 62%

The effect of physical and chemical aerosol properties on warm cloud droplet activation

et al. 2006

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Abstract. The effects of atmospheric aerosol on climate forcing may be very substantial but are quantified poorly at present; in particular, the effects of aerosols on cloud radiative properties, or the "indirect effects" are credited with the greatest range of uncertainty amongst the known causes of radiative forcing. This manuscript explores the effects that the composition and properties of atmospheric aerosol can have on the activation of droplets in warm clouds, so potentially influencing the magnitude of the indirect effect. The effects of size, composition, mixing state and various derived properties are assessed and a range of these properties provided by atmospheric measurements in a variety of locations is briefly reviewed. The suitability of a range of process-level descriptions to capture these aerosol effects is investigated by assessment of their sensitivities to uncertainties in aerosol properties and by their performance in closure studies. The treatment of these effects within global models is reviewed and suggestions for future investigations are made.

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Section: Ccn Measurementmentioning

confidence: 62%

The effect of physical and chemical aerosol properties on warm cloud droplet activation

et al. 2006

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“…Work conducted in the 1970s revealed discrepancies in the direction that we report in Table 4 (S eff /S nom Ͻ 1; Katz and Kocmond 1973) and also consistency among nominal and effective supersaturations (Gerber et al 1977). Working with Wyoming CCN instruments, both Leaitch et al (1999) and Bilde and Svenningsson (2004) reported effective and nominal supersaturations.…”

Section: H Chamber Calibration-discussionmentioning

confidence: 99%

Supersaturation in the Wyoming CCN Instrument

Snider

Petters

Wechsler

et al. 2006

Journal of Atmospheric and Oceanic Technology

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Two thermal diffusion cloud condensation nuclei (CCN) instruments were intercompared using a nearly monodisperse test aerosol composed of sodium chloride and ammonium sulfate. The main objective of this work is the determination of the maximum steady-state supersaturation within a thermal diffusion chamber. This required analysis of the uncertainties associated with the calibration of the instrument's plate temperature and light scattering measurement systems.The fraction of test particles activating to form cloud droplets, the activated fraction, was evaluated over a range of dry particle diameters at four supersaturations. Values of both the particle size, corresponding to an activated fraction equal to 0.5, and the width of a fitted activation function were derived. The former was used to evaluate the maximum steady-state chamber supersaturation. These studies reveal three significant findings. First, the derived chamber supersaturation is ϳ40% smaller than values based on temperature measured at the top and bottom of the diffusion chamber. Second, using deliquesced test particles, mobility selected at a prescribed relative humidity, it is shown that the 40% discrepancy is not the result of a test particle shape effect. Third, the width of the activation function is substantially larger than the width of the test particle size spectra.Plausible explanations for the 40% bias are considered. Contributors are the unintentional overestimation of the temperature difference imposed across the CCN chamber and the implicit assumption that water at the top and bottom of the CCN chamber has a vapor pressure equal to that over pure water.

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“…Köhler Theory provides the framework used to describe cloud droplet formation from activation of soluble particles [ Cruz and Pandis , 1997; Gerber et al , 1977; Katz and Kocmond , 1973]. A single‐parameter expression of Köhler theory, referred to as κ‐Köhler theory, was introduced by Petters and Kreidenweis [2007] to account for the effect of variations in solute hygroscopicity on CCN activity.…”

Section: Methodsmentioning

confidence: 99%

Ozone oxidation of oleic acid surface films decreases aerosol cloud condensation nuclei activity

Schwier¹,

Sareen²,

Lathem³

et al. 2011

J. Geophys. Res.

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[1] Heterogeneous oxidation of aerosols composed of pure oleic acid (C 18 H 34 O 2 , an unsaturated fatty acid commonly found in continental and marine aerosol) by gas-phase O 3 is known to increase aerosol hygroscopicity and activity as cloud condensation nuclei (CCN). Whether this trend is preserved when the oleic acid is internally mixed with other electrolytes is unknown and addressed in this study. We quantify the CCN activity of sodium salt aerosols (NaCl and Na 2 SO 4 ) internally mixed with sodium oleate (SO) and oleic acid (OA). We find that particles containing roughly one monolayer of SO/OA show similar CCN activity to pure salt particles, whereas a tenfold increase in organic concentration slightly depresses CCN activity. O 3 oxidation of these multicomponent aerosols has little effect on the critical diameter for CCN activation for unacidified particles at all conditions studied, and the activation kinetics of the CCN are similar in each case to those of pure salts. SO-containing particles which are acidified to atmospherically relevant pH before analysis in order to form oleic acid, however, show depressed CCN activity upon oxidation. This effect is more pronounced at higher organic concentrations. The behavior after oxidation is consistent with the disappearance of the organic surface film, supported by Köhler Theory Analysis (KTA). The -Köhler calculations show a small decrease in hygroscopicity after oxidation. The important implication of this finding is that oxidative aging may not always enhance the hygroscopicity of internally mixed inorganic-organic aerosols.

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An Investigation of the Size-Supersaturation Relationship of Soluble Condensation Nuclei

Cited by 21 publications

References 0 publications

The effect of physical and chemical aerosol properties on warm cloud droplet activation

The effect of physical and chemical aerosol properties on warm cloud droplet activation

Supersaturation in the Wyoming CCN Instrument

Ozone oxidation of oleic acid surface films decreases aerosol cloud condensation nuclei activity

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