Contribution of mixing to upward transport across the tropical tropopause layer (TTL)

During the second part of the TROCCINOX campaign that took place in Brazil in early 2005, chemical species were measured on-board the high-altitude research aircraft Geophysica (ozone, water vapor, NO, NOy, CH4 and CO) i
During the second part of the TROCCINOX campaign that took place in Brazil in early 2005, chemical species were measured on-board the high-altitude research aircraft Geophysica (ozone, water vapor, NO, NOy, CH4 and CO) in the altitude range up to 20 km (or up to 450 K potential temperature), i.e. spanning the entire TTL region roughly extending between 350 and 420 K. Here, analysis of transport across the TTL is performed using a new version of the Chemical Lagrangian Model of the Stratosphere (CLaMS). In this new version, the stratospheric model has been extended to the earth surface. Above the tropopause, the isentropic and cross-isentropic advection in CLaMS is driven by meteorological analysis winds and heating/cooling rates derived from a radiation calculation. Below the tropopause, the model smoothly transforms from the isentropic to the hybrid-pressure coordinate and, in this way, takes into account the effect of large-scale convective transport as implemented in the vertical wind of the meteorological analysis. As in previous CLaMS simulations, the irreversible transport, i.e. mixing, is controlled by the local horizontal strain and vertical shear rates. Stratospheric and tropospheric signatures in the TTL can be seen both in the observations and in the model. The composition of air above ≈350 K is mainly controlled by mixing on a time scale of weeks or even months. Based on CLaMS transport studies where mixing can be completely switched off, we deduce that vertical mixing, mainly driven by the vertical shear in the tropical flanks of the subtropical jets and, to some extent, in the the outflow regions of the large-scale convection, offers an explanation for the upward transport of trace species from the main convective outflow at around 350 K up to the tropical tropopause around 380 K.
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Author:Paul Konopka, Gebhard Günther, Rolf Müller, Fábio Henrique Silva dos Santos, Cornelius Schiller, Fabrizio Ravegnani, Alexey Ulanovsky, Hans Schlager, C.-Michael Volk, Silvia Viciani, Laura L. Pan, Daniel-S. McKenna, Martin Riese
URN:urn:nbn:de:hebis:30-62820
DOI:http://dx.doi.org/10.5194/acp-7-3285-2007
ISSN:1680-7316
ISSN:1680-7324
Parent Title (English):Atmospheric chemistry and physics
Publisher:European Geosciences Union
Place of publication:Katlenburg-Lindau
Document Type:Article
Language:English
Date of Publication (online):2007/06/26
Date of first Publication:2007/06/26
Publishing Institution:Univ.-Bibliothek Frankfurt am Main
Release Date:2009/03/18
Volume:7
Pagenumber:24
First Page:3285
Last Page:3308
Note:
© Author(s) 2007. This work is licensed under a Creative Commons License.
HeBIS PPN:21058145X
Institutes:Geowissenschaften
Dewey Decimal Classification:550 Geowissenschaften
Sammlungen:Universitätspublikationen
Licence (German):License LogoCreative Commons - Namensnennung 3.0

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