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| Titel |
On the temporal structure of the extratropical UTLS |
| VerfasserIn |
Peter Hoor, Heini Wernli, Michaela Hegglin, Harald Bönisch |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250058146
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| Zusammenfassung |
| The extratropical UTLS has been identified as a transition region between the troposphere
and stratosphere. It’s composition is therefore affected by the large scale Brewer-Dobson
circulation and rapid and frequent exchange across the extratropcal tropopause. A third
important pathway constitutes quasi horizontal transport from the tropics to high latitudes in
the tropical controlled layer above the tropical tropopause. These processes have different
time scales and seasonalities affecting tracers with different properties in a different
way.
We will present results of comprehensive backward trajectory calculations of 90 days and
270 days, respectively, to investigate the temporal structure of the lower stratosphere. We will
demonstrate, that the key quantity, which determines the tracer abundance in the
stratosphere is time since tropopause crossing. We will show, that the distribution of
CO relative to the tropopause and it’s correlation with ozone can be used to define
different transport regimes close to the tropopause. These correspond to different
probability for time scales of tropopause crossing and as well as transport times from the
tropopause.
We will also show, that CO can be used to identify the bottom of the tropical pipe and it’s
effect on transport to high latitudes. The transition is located around Î=460K in summer and
440K in winter. |
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