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| Titel |
Size-resolved aerosol composition and its link to hygroscopicity at a forested site in Colorado |
| VerfasserIn |
E. J. T. Levin, A. J. Prenni, B. B. Palm, D. A. Day, P. Campuzano-Jost, P. M. Winkler, S. M. Kreidenweis, P. J. DeMott, J. L. Jimenez, J. N. Smith |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 5 ; Nr. 14, no. 5 (2014-03-14), S.2657-2667 |
| Datensatznummer |
250118483
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| Publikation (Nr.) |
 copernicus.org/acp-14-2657-2014.pdf |
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| Zusammenfassung |
| Aerosol hygroscopicity describes the ability of a particle to take up water
and form a cloud droplet. Modeling studies have shown sensitivity of
precipitation-producing cloud systems to the availability of aerosol
particles capable of serving as cloud condensation nuclei (CCN), and
hygroscopicity is a key parameter controlling the number of available CCN.
Continental aerosol is typically assumed to have a representative
hygroscopicity parameter, κ, of 0.3; however, in remote locations
this value can be lower due to relatively large mass fractions of organic
components. To further our understanding of aerosol properties in remote
areas, we measured size-resolved aerosol chemical composition and
hygroscopicity in a forested, mountainous site in Colorado during the
six-week BEACHON-RoMBAS (Bio-hydro-atmosphere interactions of Energy, Aerosols,
Carbon, H2O, Organics and Nitrogen–Rocky Mountain Biogenic
Aerosol Study) campaign. This campaign followed a year-long
measurement period at this site, and results from the intensive campaign
shed light on the previously reported seasonal cycle in aerosol
hygroscopicity. New particle formation events were observed routinely at
this site and nucleation mode composition measurements indicated that the
newly formed particles were predominantly organic. These events likely
contribute to the dominance of organic species at smaller sizes, where
aerosol organic mass fractions were between 70 and 90%. Corresponding
aerosol hygroscopicity was observed to be in the range κ = 0.15–0.22,
with hygroscopicity increasing with particle size. Aerosol chemical
composition measured by an aerosol mass spectrometer and calculated from
hygroscopicity measurements agreed very well during the intensive study, with
an assumed value of κorg = 0.13 resulting in the best
agreement. |
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