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| Titel |
The impact of overshooting deep convection on local transport and mixing in the tropical upper troposphere/lower stratosphere (UTLS) |
| VerfasserIn |
W. Frey, R. Schofield, P. Hoor, D. Kunkel, F. Ravegnani, A. Ulanovsky, S. Viciani, F. D'Amato, T. P. Lane |
| 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 ; 15, no. 11 ; Nr. 15, no. 11 (2015-06-12), S.6467-6486 |
| Datensatznummer |
250119810
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| Publikation (Nr.) |
 copernicus.org/acp-15-6467-2015.pdf |
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| Zusammenfassung |
| In this study we examine the simulated downward transport and mixing of
stratospheric air into the upper tropical troposphere as observed on a
research flight during the SCOUT-O3 campaign in connection with a deep
convective system. We use the Advanced Research Weather and Research
Forecasting (WRF-ARW) model with a horizontal resolution of 333 m to examine
this downward transport. The simulation reproduces the deep convective
system, its timing and overshooting altitudes reasonably well compared to
radar and aircraft observations. Passive tracers initialised at pre-storm
times indicate the downward transport of air from the stratosphere to the
upper troposphere as well as upward transport from the boundary layer into
the cloud anvils and overshooting tops. For example, a passive ozone tracer
(i.e. a tracer not undergoing chemical processing) shows an enhancement in
the upper troposphere of up to about 30 ppbv locally in the cloud, while the
in situ measurements show an increase of 50 ppbv. However, the passive
carbon monoxide tracer exhibits an increase, while the observations show a
decrease of about 10 ppbv, indicative of an erroneous model representation
of the transport processes in the tropical tropopause layer. Furthermore, it
could point to insufficient entrainment and detrainment in the model. The
simulation shows a general moistening of air in the lower stratosphere, but
it also exhibits local dehydration features. Here we use the model to explain
the processes causing the transport and also expose areas of inconsistencies
between the model and observations. |
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