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| Titel |
Generation of layering in the upper arctic troposphere away from the jet stream |
| VerfasserIn |
A. Karpetchko, E. Kyrö, P. Gathen |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 21, no. 7 ; Nr. 21, no. 7, S.1653-1665 |
| Datensatznummer |
250014669
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| Publikation (Nr.) |
 copernicus.org/angeo-21-1653-2003.pdf |
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| Zusammenfassung |
Ozone sounding databases
for two stations, So-dankylä (67° N, 27° E) and Ny-Ålesund (79° N, 12° E)
were used in order to investigate the generation of layering in the upper and
middle troposphere of the Arctic. We concentrated on dry, ozone-rich and stable
layers observed below the thermal tropopause under light wind conditions. This
condition ensures that the observed layer is not a tropopause fold, a
well-known phenomenon that develops within frontal zones near the jet stream.
Selection criteria for ozone, humidity and stability anomalies of the
tropopause fold detection algorithm were used here to pick out for detailed
studies the most pronounced examples of laminae. For all these cases the
meteorological situations were investigated in order to establish the origin of
the observed layers. We found that layers could be classified into two groups.
Laminae of the first group were observed equatorward of the jet stream and
those of a second group were observed poleward of the jet. The meteorological
situation for the first group resembles that for equatorward stratospheric
streamer propagation. It was found that this group accounts for only a small
fraction of the layers observed at Sodankylä and for none of those observed at
Ny-Ålesund during the period investigated. A large case-to-case variability in
the synoptic situation was observed for the second group of laminae, which were
detected northward of the jet stream. Nevertheless, in about half of the cases,
streamers of tropospheric air were found in the vicinity of the stations on the
isentropic surfaces just above the detected stratospheric layers. Back
trajectory analyses showed that these layers originated in the vicinity of the
polar jet stream. We suppose that laminae-like structures in the troposphere
were caused, in both groups, by equatorward (poleward) advection of the
stratospheric (tropospheric) air, together with differential vertical shear.
Forward-trajectory calculations suggest that, subsequently, a part of the
stratospheric layers can mix irreversibly into the troposphere.
Key words. Atmospheric composition
and structure (pressure, density, and temperature; troposphere-composition and
chemistry) |
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