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| Titel |
Observations of meteoric material and implications for aerosol nucleation in the winter Arctic lower stratosphere derived from in situ particle measurements |
| VerfasserIn |
J. Curtius, R. Weigel, H.-J. Vössing, H. Wernli, A. Werner, C.-M. Volk, P. Konopka, M. Krebsbach, C. Schiller, A. Roiger, H. Schlager, V. Dreiling, S. Borrmann |
| 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 ; 5, no. 11 ; Nr. 5, no. 11 (2005-11-15), S.3053-3069 |
| Datensatznummer |
250003149
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| Publikation (Nr.) |
 copernicus.org/acp-5-3053-2005.pdf |
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| Zusammenfassung |
| Number concentrations of total and non-volatile aerosol particles with size
diameters >0.01 μm as well as particle size distributions (0.4–23 μm
diameter) were measured in situ in the Arctic lower stratosphere (10–20.5 km
altitude). The measurements were obtained during the campaigns European
Polar Stratospheric Cloud and Lee Wave Experiment (EUPLEX) and
Envisat-Arctic-Validation (EAV). The campaigns were based in Kiruna, Sweden,
and took place from January to March 2003. Measurements were conducted
onboard the Russian high-altitude research aircraft Geophysica using the
low-pressure Condensation Nucleus Counter COPAS (COndensation
PArticle Counter System) and a modified FSSP 300
(Forward Scattering Spectrometer Probe). Around 18–20 km altitude typical
total particle number concentrations nt range at 10–20 cm−3 (ambient
conditions). Correlations with the trace gases nitrous oxide (N2O) and
trichlorofluoromethane (CFC-11) are discussed. Inside the polar vortex the
total number of particles >0.01 μm increases with potential
temperature while N2O is decreasing which indicates a source of
particles in the above polar stratosphere or mesosphere. A separate channel
of the COPAS instrument measures the fraction of aerosol particles
non-volatile at 250°C. Inside the polar vortex a much higher fraction of
particles contained non-volatile residues than outside the vortex (~67%
inside vortex, ~24% outside vortex). This is most likely
due to a strongly increased fraction of meteoric material in the particles
which is transported downward from the mesosphere inside the polar vortex.
The high fraction of non-volatile residual particles gives therefore
experimental evidence for downward transport of mesospheric air inside the
polar vortex. It is also shown that the fraction of non-volatile residual
particles serves directly as a suitable experimental vortex tracer.
Nanometer-sized meteoric smoke particles may also serve as nuclei for the
condensation of gaseous sulfuric acid and water in the polar vortex and
these additional particles may be responsible for the increase in the
observed particle concentration at low N2O. The number concentrations
of particles >0.4 μm measured with the FSSP decrease markedly inside
the polar vortex with increasing potential temperature, also a consequence
of subsidence of air from higher altitudes inside the vortex. Another focus
of the analysis was put on the particle measurements in the lowermost
stratosphere. For the total particle density relatively high number
concentrations of several hundred particles per cm3 at altitudes below
~14 km were observed in several flights. To investigate the origin of
these high number concentrations we conducted air mass trajectory
calculations and compared the particle measurements with other trace gas
observations. The high number concentrations of total particles in the
lowermost stratosphere are probably caused by transport of originally
tropospheric air from lower latitudes and are potentially influenced by
recent particle nucleation. |
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