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Subarctic atmospheric aerosol composition: 3. Measured and modeled properties of cloud condensation nuclei

Kammermann, Lukas; Gysel, Martin; Weingartner, Ernest; Herich, Hanna; Cziczo, Daniel J.; Holst, Thomas LU ; Svenningsson, Birgitta LU ; Arneth, Almut LU and Baltensperger, Urs (2010) In Journal of Geophysical Research 115.
Abstract
Aerosol particles can modify cloud properties by acting as cloud condensation nuclei (CCN). Predicting CCN properties is still a challenge and not properly incorporated in current climate models. Atmospheric particle number size distributions, hygroscopic growth factors, and polydisperse CCN number concentrations were measured at the remote subarctic Stordalen mire, 200 km north of the Arctic Circle in northern Sweden. The CCN number concentration was highly variable, largely driven by variations in the total number of sufficiently large particles, though the variability of chemical composition was increasingly important for decreasing supersaturation. The hygroscopicity of particles measured by a hygroscopicity tandem differential... (More)
Aerosol particles can modify cloud properties by acting as cloud condensation nuclei (CCN). Predicting CCN properties is still a challenge and not properly incorporated in current climate models. Atmospheric particle number size distributions, hygroscopic growth factors, and polydisperse CCN number concentrations were measured at the remote subarctic Stordalen mire, 200 km north of the Arctic Circle in northern Sweden. The CCN number concentration was highly variable, largely driven by variations in the total number of sufficiently large particles, though the variability of chemical composition was increasingly important for decreasing supersaturation. The hygroscopicity of particles measured by a hygroscopicity tandem differential mobility analyzer (HTDMA) was in agreement with large critical diameters observed for CCN activation (kappa approximate to 0.07-0.21 for D = 50-200 nm). Size distribution and time- and size-resolved HTDMA data were used to predict CCN number concentrations. Agreement of predictions with measured CCN within +/- 11% was achieved using parameterized Kohler theory and assuming a surface tension of pure water. The sensitivity of CCN predictions to various simplifying assumptions was further explored: We found that (1) ignoring particle mixing state did not affect CCN predictions, (2) averaging the HTDMA data in time with retaining the size dependence did not introduce a substantial bias, while individual predictions became more uncertain, and (3) predictions involving the hygroscopicity parameter recommended in literature for continental sites (kappa approximate to 0.3 +/- 0.1) resulted in a significant prediction bias. Future modeling studies should therefore at least aim at using averaged, size-resolved, site-specific hygroscopicity or chemical composition data for predictions of CCN number concentrations. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Geophysical Research
volume
115
publisher
American Geophysical Union
external identifiers
  • wos:000274789500002
  • scopus:77649145861
ISSN
2156-2202
DOI
10.1029/2009JD012447
project
MERGE
language
English
LU publication?
yes
id
10794e05-ebd9-442c-8d8a-c121b2a075c7 (old id 1568102)
date added to LUP
2010-03-24 11:31:20
date last changed
2018-06-03 03:20:00
@article{10794e05-ebd9-442c-8d8a-c121b2a075c7,
  abstract     = {Aerosol particles can modify cloud properties by acting as cloud condensation nuclei (CCN). Predicting CCN properties is still a challenge and not properly incorporated in current climate models. Atmospheric particle number size distributions, hygroscopic growth factors, and polydisperse CCN number concentrations were measured at the remote subarctic Stordalen mire, 200 km north of the Arctic Circle in northern Sweden. The CCN number concentration was highly variable, largely driven by variations in the total number of sufficiently large particles, though the variability of chemical composition was increasingly important for decreasing supersaturation. The hygroscopicity of particles measured by a hygroscopicity tandem differential mobility analyzer (HTDMA) was in agreement with large critical diameters observed for CCN activation (kappa approximate to 0.07-0.21 for D = 50-200 nm). Size distribution and time- and size-resolved HTDMA data were used to predict CCN number concentrations. Agreement of predictions with measured CCN within +/- 11% was achieved using parameterized Kohler theory and assuming a surface tension of pure water. The sensitivity of CCN predictions to various simplifying assumptions was further explored: We found that (1) ignoring particle mixing state did not affect CCN predictions, (2) averaging the HTDMA data in time with retaining the size dependence did not introduce a substantial bias, while individual predictions became more uncertain, and (3) predictions involving the hygroscopicity parameter recommended in literature for continental sites (kappa approximate to 0.3 +/- 0.1) resulted in a significant prediction bias. Future modeling studies should therefore at least aim at using averaged, size-resolved, site-specific hygroscopicity or chemical composition data for predictions of CCN number concentrations.},
  author       = {Kammermann, Lukas and Gysel, Martin and Weingartner, Ernest and Herich, Hanna and Cziczo, Daniel J. and Holst, Thomas and Svenningsson, Birgitta and Arneth, Almut and Baltensperger, Urs},
  issn         = {2156-2202},
  language     = {eng},
  publisher    = {American Geophysical Union},
  series       = {Journal of Geophysical Research},
  title        = {Subarctic atmospheric aerosol composition: 3. Measured and modeled properties of cloud condensation nuclei},
  url          = {http://dx.doi.org/10.1029/2009JD012447},
  volume       = {115},
  year         = {2010},
}