Field measurements of hygroscopic properties and state of mixing of nucleation mode particles

Väkevä, M.; Kulmala, Markku; Stratmann, Frank; Hämeri, Kaarle

doi:10.5194/acp-2-55-2002

Cited by 41 publications

(24 citation statements)

References 36 publications

(41 reference statements)

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“…7a and c). This diurnal trend corresponds well with those found by previous studies at the Hyytiälä site (e.g., Hämeri et al, 2001;Väkevä et al, 2002;Boy et al, 2004;Ehn et al, 2007). CFSTGC-derived κ values covary with AMS-derived inorganic volume fraction, daily temperature trends, and AMS f 44 data.…”

Section: Diurnal Variability Of κsupporting

confidence: 89%

Aerosol hygroscopicity and CCN activation kinetics in a boreal forest environment during the 2007 EUCAARI campaign

et al. 2011

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Abstract. Measurements of size-resolved cloud condensation nuclei (CCN) concentrations, subsaturated hygroscopic growth, size distribution, and chemical composition were collected from March through May, 2007, in the remote Boreal forests of Hyytiälä, Finland, as part of the European Integrated project on Aerosol Cloud Climate and Air Quality Interactions (EUCAARI) campaign. Hygroscopicity parameter, κ, distributions were derived independently from Continuous Flow-Streamwise Thermal Gradient CCN Chamber (CFSTGC) and Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA) measurements. CFSTGC-derived κ values for 40, 60, and 80 nm particles range mostly between 0.10 and 0.40 with an average characteristic of highly oxidized organics of 0.20 ± 0.10, indicating that organics play a dominant role for this environment. HTDMA-derived κ were generally 30 % lower. Diurnal trends of κ show a minimum at sunrise and a maximum in the late afternoon; this trend covaries with inorganic mass fraction and the m/z 44 organic mass fraction given by a quadrupole aerosol mass spectrometer, further illustrating the importance of organCorrespondence to: A. Nenes (athanasios.nenes@gatech.edu) ics in aerosol hygroscopicity. The chemical dispersion inferred from the observed κ distributions indicates that while 60 and 80 nm dispersion increases around midday, 40 nm dispersion remains constant. Additionally, 80 nm particles show a markedly higher level of chemical dispersion than both 40 and 60 nm particles. An analysis of droplet activation kinetics for the sizes considered indicates that most of the CCN activate as rapidly as (NH 4 ) 2 SO 4 calibration aerosol.

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Section: Diurnal Variability Of κsupporting

confidence: 89%

Aerosol hygroscopicity and CCN activation kinetics in a boreal forest environment during the 2007 EUCAARI campaign

et al. 2011

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“…Freshly emitted hydrophobic particles such as externally mixed black carbon particles are mostly in the fine modes. Besides, the significant Kelvin effect also leads to higher hygroscopic growth factors for particles in the coarse mode than for those in fine modes (Väkevä et al, 2002). For the coarse mode, the R 2 are between 0.3 and 0.6 under all the RH conditions.…”

Section: Impacts Of Pnsdmentioning

confidence: 90%

A study of aerosol liquid water content based on hygroscopicity measurements at high relative humidity in the North China Plain

et al. 2014

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Abstract. Water can be a major component of aerosol particles, also serving as a medium for aqueous-phase reactions. In this study, a novel method is presented to calculate the aerosol liquid water content at high relative humidity based on measurements of aerosol hygroscopic growth factor, particle number size distribution and relative humidity in the Haze in China (HaChi) summer field campaign (July-August 2009) in the North China Plain. The aerosol liquid water content calculated using this method agreed well with that calculated using a thermodynamic equilibrium model (ISORROPIA II) at high relative humidity (> 60 %) with a correlation coefficient of 0.96. At low relative humidity (< 60 %), an underestimation was found in the calculated aerosol liquid water content by the thermodynamic equilibrium model. This discrepancy mainly resulted from the ISORROPIA II model, which only considered limited aerosol chemical compositions. The mean and maximum values of aerosol liquid water content during the HaChi campaign reached 1.69 × 10 −4 g m −3 and 9.71 × 10 −4 g m −3 , respectively. A distinct diurnal variation of the aerosol liquid water content was found, with lower values during daytime and higher ones at night. The aerosol liquid water content depended strongly on the relative humidity. The aerosol liquid water content in the accumulation mode dominated the total aerosol liquid water content.

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“…The ratio of the calculated to the measured CCN concentration for different mass fraction of ammonium sulfate (from 1.0 to 0.1) and five supersaturations is shown in Secondly, we assume that ammonium sulfate is externally mixed with insoluble material. Externally mixed aerosols were observed at many places (e.g., Väkevä et al, 2002) and have been assumed in many regional scale models (Koch et al, 1999;Chin et al, 2000;Boucher and Anderson, 1995;Barth et al, 2000). The insoluble aerosols are hydrophobic and do not act as CCN.…”

Section: Sensitivity To Aerosol Solubility and Mixing Statementioning

confidence: 99%

“…Two different types of mixture, internal mixture and external mixture, are often observed in field measurements (Väkevä et al, 2002;Schwarz et al, 2006) and used in model studies (Textor et al, 2006;Wang et al, 2010). For example, field measurements by Väkevä et al (2002) showed that externally mixed aerosol was sometimes observed at urban and forest sites in Finland and a coastal site in western Ireland. Schwarz et al (2006) presented results that the number fraction of internally mixed black carbon particles range from 0.2 to 0.8.…”

Section: F Yang Et Al: a Closure Study Of Cloud Condensation Nucleimentioning

confidence: 99%

“…In addition to the chemical composition of aerosol, the size distribution, the mixing state and a detailed knowledge of how different compounds interact with water, are required to accurately predict how a realistic aerosol population will undergo cloud nucleation (Andreae and Rosenfeld, 2008;McFiggans et al, 2006;Ward et al, 2010). Two different types of mixture, internal mixture and external mixture, are often observed in field measurements (Väkevä et al, 2002;Schwarz et al, 2006) and used in model studies (Textor et al, 2006;Wang et al, 2010). For example, field measurements by Väkevä et al (2002) showed that externally mixed aerosol was sometimes observed at urban and forest sites in Finland and a coastal site in western Ireland.…”

Section: F Yang Et Al: a Closure Study Of Cloud Condensation Nucleimentioning

confidence: 99%

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A closure study of cloud condensation nuclei in the North China Plain using droplet kinetic condensational growth model

et al. 2012

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Abstract. Aerosol size distribution and cloud condensation nucleus (CCN) number concentration were measured in the North China Plain from 31 December 2009 to 20 January 2010. The CCN closure study was performed using these data and droplet kinetic condensational growth model. The calculated CCN concentration with the assumption of pure ammonium sulfate aerosol is 40-140 % higher than that observed for the supersaturations in this study. A sensitivity test on aerosol solubility and mixing state indicates that 0.2-0.5 mass fraction of ammonium sulfate for internal mixture can lead to a ratio of 0.82-1.30 for the calculated to observed CCN concentrations, and that 0.4-0.7 mass fraction of ammonium sulfate for external mixture results in a ratio of 0.74-1.25 in the North China Plain during the time period of the field observations, suggesting that a relatively simple scheme may be used for CCN prediction in climate models for this region. Finally, we compare the calculated CCN concentrations from the kinetic condensational growth model and the equilibrium model. The kinetic condensational growth model can simulate droplet growth in a time period under a certain supersaturation, while the equilibrium model only predicts whether a certain aerosol can be activated as CCN under that supersaturation. The CCN concentration calculated with the kinetic model is higher than that with the equilibrium model at supersaturations of 0.056 % and 0.083 %, because some particles that are not activated from the equilibrium pointof-view can grow large enough to be considered as CCN in the kinetic model. While at a supersaturation of 0.17 %, CCN concentration calculated with the kinetic model is lower than that with the equilibrium model, due to the limitation of droplet kinetic growth. The calculated CCN concentrations using the kinetic model and the equilibrium model are the same at supersaturations of 0.35 % and 0.70 %.

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Field measurements of hygroscopic properties and state of mixing of nucleation mode particles

Cited by 41 publications

References 36 publications

Aerosol hygroscopicity and CCN activation kinetics in a boreal forest environment during the 2007 EUCAARI campaign

Aerosol hygroscopicity and CCN activation kinetics in a boreal forest environment during the 2007 EUCAARI campaign

A study of aerosol liquid water content based on hygroscopicity measurements at high relative humidity in the North China Plain

A closure study of cloud condensation nuclei in the North China Plain using droplet kinetic condensational growth model

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