Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 4 6 2004 10.5194/acpd-4-7167-2004 http://www.atmos-chem-phys-discuss.net/4/7167/2004/ http://www.atmos-chem-phys-discuss.net/4/7167/2004/acpd-4-7167-2004.html http://www.atmos-chem-phys-discuss.net/4/7167/2004/acpd-4-7167-2004.pdf 7167 7180 2004-11-05 Technical Note: The new comprehensive atmospheric chemistry module MECCA R. Sander R. Kerkweg P. Jöckel J. Lelieveld Air Chemistry Department, Max-Planck Institute of Chemistry, P.O. Box 3060, 55020 Mainz, Germany 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 O₃, CH₄, HO_x, and NO_x, 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 kind of model, from a simple box model to a sophisticated global general circulation model.