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| Titel |
Origin of aerosol particles in the mid-latitude and subtropical upper troposphere and lowermost stratosphere from cluster analysis of CARIBIC data |
| VerfasserIn |
M. Köppe, M. Hermann, C. A. M. Brenninkmeijer, J. Heintzenberg, H. Schlager, T. Schuck, F. Slemr, D. Sprung, P. F. J. Velthoven, A. Wiedensohler, A. Zahn, H. Ziereis |
| 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 ; 9, no. 21 ; Nr. 9, no. 21 (2009-11-05), S.8413-8430 |
| Datensatznummer |
250007733
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| Publikation (Nr.) |
 copernicus.org/acp-9-8413-2009.pdf |
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| Zusammenfassung |
| The origin of aerosol particles in the upper troposphere and lowermost
stratosphere over the Eurasian continent was investigated by applying
cluster analysis methods to in situ measured data. Number concentrations of
submicrometer aerosol particles and trace gas mixing ratios derived by the
CARIBIC (Civil Aircraft for Regular Investigation of the Atmosphere Based on
an Instrument Container) measurement system on flights between Germany and
South-East Asia were used for this analysis. Four cluster analysis methods
were applied to a test data set and their capability of separating the data
points into scientifically reasonable clusters was assessed. The best method
was applied to seasonal data subsets for summer and winter resulting in five
cluster or air mass types: stratosphere, tropopause, free troposphere, high
clouds, and boundary layer influenced. Other source clusters, like aircraft
emissions could not be resolved in the present data set with the used
methods. While the cluster separation works satisfactory well for the summer
data, in winter interpretation is more difficult, which is attributed to
either different vertical transport pathways or different chemical lifetimes
in both seasons. The geographical distribution of the clusters together with
histograms for nucleation and Aitken mode particles within each cluster are
presented. Aitken mode particle number concentrations show a clear vertical
gradient with the lowest values in the lowermost stratosphere (750–2820 particles/cm3 STP,
minimum of the two 25% – and maximum of the two
75%-percentiles of both seasons) and the highest values for the
boundary-layer-influenced air (4290–22 760 particles/cm3 STP).
Nucleation mode particles are also highest in the boundary-layer-influenced
air (1260–29 500 particles/cm3 STP), but are lowest in the free
troposphere (0–450 particles/cm3 STP). The given submicrometer
particle number concentrations represent the first large-scale seasonal data
sets for the upper troposphere and lowermost stratosphere over the Eurasian
continent. |
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