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A closure study of sub-micrometer aerosol particle hygroscopic behaviour

Swietlicki, Erik LU ; Zhou, Jingchuan LU ; Berg, Olle H. ; Martinsson, Bengt G. LU ; Frank, Göran LU ; Cederfelt, Sven Inge ; Dusek, Ulrike ; Berner, Axel ; Birmili, Wolfram and Wiedensohler, Alfred , et al. (1999) In Atmospheric Research 50(3-4). p.205-240
Abstract

The hygroscopic properties of sub-micrometer aerosol particles were studied in connection with a ground-based cloud experiment at Great Dun Fell, in northern England in 1995. Hygroscopic diameter growth factors were measured with a Tandem Differential Mobility Analyser (TDMA) for dry particle diameters between 35 and 265 nm at one of the sites upwind of the orographic cloud. An external mixture consisting of three groups of particles, each with different hygroscopic properties, was observed. These particle groups were denoted less-hygroscopic, more-hygroscopic and sea spray particles and had average diameter growth factors of 1.11-1.15, 1.38-1.69 and 2.08-2.21 respectively when taken from a dry state to a relative humidity of 90%.... (More)

The hygroscopic properties of sub-micrometer aerosol particles were studied in connection with a ground-based cloud experiment at Great Dun Fell, in northern England in 1995. Hygroscopic diameter growth factors were measured with a Tandem Differential Mobility Analyser (TDMA) for dry particle diameters between 35 and 265 nm at one of the sites upwind of the orographic cloud. An external mixture consisting of three groups of particles, each with different hygroscopic properties, was observed. These particle groups were denoted less-hygroscopic, more-hygroscopic and sea spray particles and had average diameter growth factors of 1.11-1.15, 1.38-1.69 and 2.08-2.21 respectively when taken from a dry state to a relative humidity of 90%. Average growth factors increased with dry particle size. A bimodal hygroscopic behaviour was observed for 74-87% of the cases depending on particle size. Parallel measurements of dry sub-micrometer particle number size distributions were performed with a Differential Mobility Particle Sizer (DMPS). The inorganic ion aerosol composition was determined by means of ion chromatography analysis of samples collected with Berner-type low pressure cascade impactors at ambient conditions. The number of ions collected on each impactor stage was predicted from the size distribution and hygroscopic growth data by means of a model of hygroscopic behaviour assuming that only the inorganic substances interacted with the ambient water vapour. The predicted ion number concentration was compared with the actual number of all positive and negative ions collected on the various impactor stages. For the impactor stage which collected particles with aerodynamic diameters between 0.17-0.53 μm at ambient relative humidity, and for which all pertinent data was available for the hygroscopic closure study, the predicted ion concentrations agreed with the measured values within the combined measurement and model uncertainties for all cases but one. For this impactor sampling occasion, the predicted ion concentration was significantly higher than the measured. The air mass in which this sample was taken had undergone extensive photochemical activity which had probably produced hygroscopically active material other than inorganic ions, such as organic oxygenated substances.

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keywords
Aerosol particles, Closure study, Hygroscopic growth, Tandem differential mobility analyser (TDMA)
in
Atmospheric Research
volume
50
issue
3-4
pages
36 pages
publisher
Elsevier
external identifiers
  • scopus:6744224445
ISSN
0169-8095
DOI
10.1016/S0169-8095(98)00105-7
language
English
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yes
id
db632408-51b8-4720-ac8f-36e75f3c272b
date added to LUP
2019-05-16 09:40:34
date last changed
2019-11-25 09:30:06
@article{db632408-51b8-4720-ac8f-36e75f3c272b,
  abstract     = {<p>The hygroscopic properties of sub-micrometer aerosol particles were studied in connection with a ground-based cloud experiment at Great Dun Fell, in northern England in 1995. Hygroscopic diameter growth factors were measured with a Tandem Differential Mobility Analyser (TDMA) for dry particle diameters between 35 and 265 nm at one of the sites upwind of the orographic cloud. An external mixture consisting of three groups of particles, each with different hygroscopic properties, was observed. These particle groups were denoted less-hygroscopic, more-hygroscopic and sea spray particles and had average diameter growth factors of 1.11-1.15, 1.38-1.69 and 2.08-2.21 respectively when taken from a dry state to a relative humidity of 90%. Average growth factors increased with dry particle size. A bimodal hygroscopic behaviour was observed for 74-87% of the cases depending on particle size. Parallel measurements of dry sub-micrometer particle number size distributions were performed with a Differential Mobility Particle Sizer (DMPS). The inorganic ion aerosol composition was determined by means of ion chromatography analysis of samples collected with Berner-type low pressure cascade impactors at ambient conditions. The number of ions collected on each impactor stage was predicted from the size distribution and hygroscopic growth data by means of a model of hygroscopic behaviour assuming that only the inorganic substances interacted with the ambient water vapour. The predicted ion number concentration was compared with the actual number of all positive and negative ions collected on the various impactor stages. For the impactor stage which collected particles with aerodynamic diameters between 0.17-0.53 μm at ambient relative humidity, and for which all pertinent data was available for the hygroscopic closure study, the predicted ion concentrations agreed with the measured values within the combined measurement and model uncertainties for all cases but one. For this impactor sampling occasion, the predicted ion concentration was significantly higher than the measured. The air mass in which this sample was taken had undergone extensive photochemical activity which had probably produced hygroscopically active material other than inorganic ions, such as organic oxygenated substances.</p>},
  author       = {Swietlicki, Erik and Zhou, Jingchuan and Berg, Olle H. and Martinsson, Bengt G. and Frank, Göran and Cederfelt, Sven Inge and Dusek, Ulrike and Berner, Axel and Birmili, Wolfram and Wiedensohler, Alfred and Yuskiewicz, Brett and Bower, Keith N.},
  issn         = {0169-8095},
  language     = {eng},
  month        = {03},
  number       = {3-4},
  pages        = {205--240},
  publisher    = {Elsevier},
  series       = {Atmospheric Research},
  title        = {A closure study of sub-micrometer aerosol particle hygroscopic behaviour},
  url          = {http://dx.doi.org/10.1016/S0169-8095(98)00105-7},
  doi          = {10.1016/S0169-8095(98)00105-7},
  volume       = {50},
  year         = {1999},
}