ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-5-445-2005 Technical note: The new comprehensive atmospheric chemistry module MECCA Sander R. 1 Kerkweg A. 1 Jöckel P. 1 Lelieveld J. 1 Air Chemistry Department, Max-Planck-Institute of Chemistry, P.O. Box 3060, 55020 Mainz, Germany 11 02 2005 5 2 445 450 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/5/445/2005/acp-5-445-2005.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/5/445/2005/acp-5-445-2005.pdf

In this technical note we present the multi-purpose atmospheric chemistry model MECCA. Owing to its versatility and modular structure, it can be used for tropospheric as well as stratospheric chemistry calculations. Extending the code to other domains (e.g. mesospheric or oceanic chemistry) is easily possible. MECCA contains a comprehensive atmospheric reaction mechanism that currently includes: 1) the basic O<sub>3</sub>, CH<sub>4</sub>, HO<sub>x</sub>, and NO<sub>x</sub> chemistry, 2) non-methane hydrocarbon (NMHC) chemistry, 3) halogen (Cl, Br, I) chemistry, and 4) sulfur chemistry. Not only gas-phase chemistry but also aqueous-phase and heterogeneous reactions are considered. Arbitrary subsets of the comprehensive mechanism can be selected according to the research objectives. The program code resulting from the chemical mechanism can easily be used in any model, from a simple box model to a comprehensive global general circulation model.