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| Titel |
The characterisation of the interaction between atmospheric aerosol and water vapour |
| VerfasserIn |
M. Irwin, J. Crosier, D. Topping, N. Good, J. Allan, G. McFiggans |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250025999
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| Zusammenfassung |
| Organic matter is not particularly hygroscopic. However, many classes of organic compounds
are known to suppress surface tension. Surface tension suppression plays a more important
role as the environmental saturation ratio increases (Wex et al., 2008) thus the incorporation
of organic material into existing inorganic particles will reduce the supersaturation required
to activate in a cloud and hence alter the number of Cloud Condensation Nuclei (CCN)
formed.
It has been hypothesised that a particles size far outweighs the of importance of
composition when referring to the activation potential of an aerosol particle (Dusek et al.,
2006) which has led to the adoption of a simplified Köhler equation, incorporating
a term kappa, κ (Petters and Kreidenweis, 2007) that takes all the composition
information and assigns it a value dependent on the particle size and growth factor.
Whilst the κ-Köhler approximation works reasonably well for inorganic salts such as
sodium chloride, κ-Köhler theory makes assumptions regarding the behaviour of
multicomponent solution properties as one extrapolates from hygroscopic growth
to CCN activation, which may potentially lead to erroneous prediction of CCN
properties.
In order to probe the κ-Köhler approximation, measured particle sub and supersaturated
water uptake have been compared using a variety of instrumentation.
A Hygroscopic Tandem Differential Mobility Analyser (HTDMA) was used to probe the
aerosol (dry diameter 26nm |
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