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| Titel |
Stratosphere-troposphere exchange in an extratropical cyclone, calculated with a Lagrangian method |
| VerfasserIn |
M. Sigmond, J. Meloen, P. C. Siegmund |
| 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 ; 18, no. 5 ; Nr. 18, no. 5, S.573-582 |
| Datensatznummer |
250013991
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| Publikation (Nr.) |
 copernicus.org/angeo-18-573-2000.pdf |
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| Zusammenfassung |
A Lagrangian technique is developed and
applied to calculate stratosphere-troposphere exchange in an extratropical
cyclone. This exchange is computed from the potential vorticity or PV
along trajectories, calculated from ECMWF circulation data. Special emphasis is
put on the statistical significance of the results. The computed field of the
cross-tropopause flux is dominated by elongated patterns of statistically
significant large downward and small upward fluxes. The downward fluxes mainly
occur in the lower part of the considered tropopause folds. The upward fluxes
are found near the entrance of the folds, in the tropopause ridges. The ratio
between the area averaged downward and upward cross-tropopause fluxes increases
with increasing strength of the cyclone. Since the largest fluxes are shown to
occur in the regions with the largest wind shear, where PV-mixing is
thought to cause large cross-tropopause fluxes, the results are expected to be
reliable, at least in a qualitative sense. The position of a tropopause fold
along the northwest coast of Africa is confirmed by total ozone observations.
The results indicate that the applied Lagrangian technique is an appropriate
tool for diagnosing stratosphere-troposphere exchange.
Key words: Meteorology and atmospheric dynamics
(general circulation; mesoscale meteorology; middle atmosphere dynamics) |
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