GMDD Geoscientific Model Development Discussions GMDD 1991-962X Copernicus GmbH Göttingen, Germany 10.5194/gmdd-3-2189-2010 A quasi chemistry-transport model mode for EMAC Deckert R. 1 Jöckel P. 1 Grewe V. 1 Gottschaldt K.-D. 1 Hoor P. 2 Deutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany Johannes Gutenberg-Universität Mainz, Institut für Physik der Atmosphäre, Mainz, Germany 19 11 2010 3 4 2189 2220 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.geosci-model-dev-discuss.net/3/2189/2010/gmdd-3-2189-2010.html The full text article is available as a PDF file from http://www.geosci-model-dev-discuss.net/3/2189/2010/gmdd-3-2189-2010.pdf

A quasi chemistry-transport model mode (QCTM) is presented for the numerical chemistry-climate simulation system ECHAM/MESSy Atmospheric Chemistry (EMAC). It allows for a quantification of chemical signals through suppression of any feedback between chemistry and dynamics. Noise would otherwise interfere too strongly. The signal follows from the difference of two QCTM simulations, reference and sensitivity. These are fed with offline chemical fields as a substitute of the feedbacks between chemistry and dynamics: offline mixing ratios of radiatively active substances enter the radiation scheme (a), offline mixing ratios of nitric acid enter the scheme for re-partitioning and sedimentation from polar stratospheric clouds (b). Offline methane oxidation is the exclusive source of chemical water-vapor tendencies (c). Any set of offline fields suffices to suppress the feedbacks, though may be inconsistent with the simulation setup. An adequate set of offline climatologies can be produced from a non-QCTM simulation of the reference setup. Test simulations reveal the particular importance of adequate offline fields associated with (a). Inconsistencies from (b) are negligible when using adequate fields of nitric acid. Acceptably small inconsistencies come from (c), but should vanish for an adequate prescription of water vapor tendencies. Toggling between QCTM and non-QCTM is done via namelist switches and does not require a source code re-compilation.

 References Buchholz, J.: Simulations of physics and chemistry of polar stratospheric clouds with a general circulation model, Ph.D thesis, Johannes Guttenberg University Mainz, 2005. Clough, S. and Iacono, M.: Line-by-line calculation of atmospheric fluxes and cooling rates 2 Application to carbon dioxide, ozone, methane, nitrous oxide and the halocarbons, J. Geophys. Res., 100, 16519–16535, 1995. Damian, V., Sandu, A., Damian, M., Potra, F., and Carmichael, G.: The kinetic preprocessor KPP – a software environment for solving chemical kinetics, Comput. Chem. Eng., 26, 1567–1579, 2002. Fomichev, V I., Jonsson, A I., de~Grandpré, J., Beagley, S R., McLandress, C., Semeniuk, K., and Shepherd, T G.: Response of the middle atmosphere to CO<sub>2</sub> doubling: results from the Canadian Middle Atmosphere Model, J. Climate, 20, 1121–1144, 2007. Fortuin, J. and Kelder, H.: An ozone climatology base on ozonesonde and satellite measurements, Clim. Dynam., 103, 31709–31734, 1998. Hoor, P., Borken-Kleefeld, J., Caro, D., Dessens, O., Endresen, O., Gauss, M., Grewe, V., Hauglustaine, D., Isaksen, I. S. A., Jöckel, P., Lelieveld, J., Myhre, G., Meijer, E., Olivie, D., Prather, M., Schnadt Poberaj, C., Shine, K. P., Staehelin, J., Tang, Q., van Aardenne, J., van Velthoven, P., and Sausen, R.: The impact of traffic emissions on atmospheric ozone and OH: results from QUANTIFY, Atmos. Chem. Phys., 9, 3113–3136, doi:10.5194/acp-9-3113-2009, 2009. Jöckel, P.: Technical note: Recursive rediscretisation of geo-scientific data in the Modular Earth Submodel System (MESSy), Atmos. Chem. Phys., 6, 3557–3562, doi:10.5194/acp-6-3557-2006, 2006. Jöckel, P., Tost, H., Pozzer, A., Brühl, C., Buchholz, J., Ganzeveld, L., Hoor, P., Kerkweg, A., Lawrence, M. G., Sander, R., Steil, B., Stiller, G., Tanarhte, M., Taraborrelli, D., van Aardenne, J., and Lelieveld, J.: The atmospheric chemistry general circulation model ECHAM5/MESSy1: consistent simulation of ozone from the surface to the mesosphere, Atmos. Chem. Phys., 6, 5067–5104, doi:10.5194/acp-6-5067-2006, 2006. Kerkweg, A., Sander, R., Tost, H., and Jöckel, P.: Technical note: Implementation of prescribed (OFFLEM), calculated (ONLEM), and pseudo-emissions (TNUDGE) of chemical species in the Modular Earth Submodel System (MESSy), Atmos. Chem. Phys., 6, 3603–3609, doi:10.5194/acp-6-3603-2006, 2006. Kirner, O., Ruhnke, R., Buchholz-Dietsch, J., Jöckel, P., Brühl, C., and Steil, B.: Simulation of polar stratospheric clouds in the chemistry-climate-model EMAC via the submodel PSC, Geosci. Model Dev. Discuss., 3, 2071–2108, doi:10.5194/gmdd-3-2071-2010, 2010. Roeckner, E., Brokopf, R., Esch, M., Giorgetta, M., Hagemann, S., Kornblueh, L., Manzini, E., Schlese, U., and Schulzweida, U.: Sensitivity of simulated climate to horizontal and vertical resolution in the ECHAM5 atmosphere model, J. Climate, 19, 3771–3791, 2006. Sander, R., Kerkweg, A., Jöckel, P., and Lelieveld, J.: Technical note: The new comprehensive atmospheric chemistry module MECCA, Atmos. Chem. Phys., 5, 445–450, doi:10.5194/acp-5-445-2005, 2005. Steil, B., Brühl, C., Manzini, E., Crutzen, P J., Lelieveld, J., Rasch, P J., Roeckner, E., and Krüger, K.: A new interactive chemistry-climate model: 1 Present-day climatology and interannual variability of the middle atmosphere using the model and 9 years of HALOE/UARS data, J. Geophys. Res., 108, D4290, \doi10.1029/2002JD002971, 2003. Unger, N., Shindell, D., Koch, D., and Streets, D.: Air pollution radiative forcing from specific emissions sectors at 2030, J. Geophys. Res., 113, D02306, \doi10.1029/2007JD008683, 2008. von Storch, H. and Zwiers, F.: Statistical analysis in climate research, Cambridge University Press, Cambridge, 1999. WMO: Scientific assessment of ozone depletion: 2006, vol 50, in: Global Ozone Res. Monit. Proj. Rep., World Meteorological Organization, Geneva, Switzerland, 2007.