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| Titel |
Hydration and dehydration at the tropical tropopause |
| VerfasserIn |
C. Schiller, J.-U. Grooß, P. Konopka, F. Plöger, F. H. Silva dos Santos, N. Spelten |
| 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. 24 ; Nr. 9, no. 24 (2009-12-23), S.9647-9660 |
| Datensatznummer |
250007814
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| Publikation (Nr.) |
 copernicus.org/acp-9-9647-2009.pdf |
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| Zusammenfassung |
| High-resolution water measurements from three tropical airborne missions in
Northern Australia, Southern Brazil and West Africa in different seasons are
analysed to study the transport and transformation of water in the tropical
tropopause layer (TTL) and its impact on the stratosphere. The mean profiles
are quite different according to the season and location of the campaigns,
with lowest mixing ratios below 2 ppmv at the cold point tropopause during
the Australian mission in November/December and high TTL mixing ratios
during the African measurements in August. We present backward trajectory
calculations considering freeze-drying of the air to the minimum saturation
mixing ratio and initialised with climatological satellite data. This
trajectory-based reconstruction of water agrees well with the observed
H2O average profiles and therefore demonstrates that the water vapour
set point in the TTL is primarily determined by the Lagrangian saturation
history. Deep convection was found to moisten the TTL, in several events
even above the cold point up to 420 K potential temperatures. However, our
study does not provide evidence for a larger impact of these
highly-localised events on global scales. |
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