ACP Atmospheric Chemistry and Physics ACP Atmos. Chem. Phys. 1680-7324 Copernicus Publications Göttingen, Germany 10.5194/acp-7-1731-2007 A numerical study of tropical cross-tropopause transport by convective overshoots Chaboureau J.-P. 1 Cammas J.-P. 1 Duron J. 1 Mascart P. J. 1 Sitnikov N. M. 2 Voessing H.-J. 3 Laboratoire d'Aérologie, Université Paul Sabatier and CNRS, Toulouse, France Central Aerological Observatory, Dolgoprudny, Russia Institute for Atmospheric Physics, University of Mainz, Germany 10 04 2007 7 7 1731 1740 Copyright: © 2007 J.-P. Chaboureau et al. 2007 This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 Generic License. To view a copy of this licence, visit https://creativecommons.org/licenses/by-nc-sa/2.5/ This article is available from https://acp.copernicus.org/articles/7/1731/2007/acp-7-1731-2007.html The full text article is available as a PDF file from https://acp.copernicus.org/articles/7/1731/2007/acp-7-1731-2007.pdf

Observations obtained during the Tropical Convection, Cirrus and Nitrogen Oxides (TROCCINOX) golden day have revealed the presence of ice particles up to 410 K (18.2 km) 2 km above the local tropopause. The case was investigated using a three-dimensional quadruply nested non-hydrostatic simulation and Meteosat Second Generation (MSG) observations. The simulation reproduced the measurements along the flight track fairly well. A reasonable agreement with MSG observations was also achieved: the 10.8-μm brightness temperature (BT) minimum of 187 K was reproduced (a value 6 K colder than the environmental cold-point temperature) as was the positive BT difference between the 6.2- and 10.8-μm bands, an overshoot signature. The simulation produced several overshooting plumes up to 410 K yielding an upward transport of water vapour of a few tons per second across the tropical tropopause. The estimated mass flux agrees with those derived from over tracer budgets, indicating that convection transports mass across the tropopause.

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