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| Titel |
Chemical composition of ambient aerosol, ice residues and cloud droplet residues in mixed-phase clouds: single particle analysis during the Cloud and Aerosol Characterization Experiment (CLACE 6) |
| VerfasserIn |
M. Kamphus, M. Ettner-Mahl, T. Klimach, F. Drewnick, L. Keller, D. J. Cziczo, S. Mertes, S. Borrmann, J. Curtius |
| 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 ; 10, no. 16 ; Nr. 10, no. 16 (2010-08-30), S.8077-8095 |
| Datensatznummer |
250008738
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| Publikation (Nr.) |
 copernicus.org/acp-10-8077-2010.pdf |
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| Zusammenfassung |
| Two different single particle mass spectrometers were operated in parallel
at the Swiss High Alpine Research Station Jungfraujoch (JFJ, 3580 m a.s.l.)
during the Cloud and Aerosol Characterization Experiment (CLACE 6) in
February and March 2007. During mixed phase cloud events ice crystals from
5–20 μm were separated from larger ice aggregates, non-activated,
interstitial aerosol particles and supercooled droplets using an
Ice-Counterflow Virtual Impactor (Ice-CVI). During one cloud period
supercooled droplets were additionally sampled and analyzed by changing the
Ice-CVI setup. The small ice particles and droplets were evaporated by
injection into dry air inside the Ice-CVI. The resulting ice and droplet
residues (IR and DR) were analyzed for size and composition by the two
single particle mass spectrometers: a custom-built Single Particle
Laser-Ablation Time-of-Flight Mass Spectrometer (SPLAT) and a commercial
Aerosol Time-of-Flight Mass Spectrometer (ATOFMS, TSI Model 3800). During
CLACE 6 the SPLAT instrument characterized 355 individual IR that produced a
mass spectrum for at least one polarity and the ATOFMS measured 152 IR. The
mass spectra were binned in classes, based on the combination of dominating
substances, such as mineral dust, sulfate, potassium and elemental carbon or
organic material. The derived chemical information from the ice residues is
compared to the JFJ ambient aerosol that was sampled while the measurement
station was out of clouds (several thousand particles analyzed by SPLAT and
ATOFMS) and to the composition of the residues of supercooled cloud droplets
(SPLAT: 162 cloud droplet residues analyzed, ATOFMS: 1094). The measurements
showed that mineral dust was strongly enhanced in the ice particle residues.
Close to all of the SPLAT spectra from ice residues did contain signatures
from mineral compounds, albeit connected with varying amounts of soluble
compounds. Similarly, close to all of the ATOFMS IR spectra show a mineral
or metallic component. Pure sulfate and nitrate containing particles were
depleted in the ice residues. Sulfate and nitrate was found to dominate the
droplet residues (~90% of the particles). The results from the two
different single particle mass spectrometers were generally in agreement.
Differences in the results originate from several causes, such as the
different wavelength of the desorption and ionisation lasers and different
size-dependent particle detection efficiencies. |
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