Journal article

Quantifying the effect of mixing on the mean age of air in CCMVal-2 and CCMI-1 models

Simone Dietmueller, Roland Eichinger, Hella Garny, Thomas Birner, Harald Boenisch, Giovanni Pitari, Eva Mancini, Daniele Visioni, Andrea Stenke, Laura Revell, Eugene Rozanov, David A Plummer, John Scinocca, Patrick Joeckel, Luke Oman, Makoto Deushi, Shibata Kiyotaka, Douglas E Kinnison, Rolando Garcia, Olaf Morgenstern Show all

Atmospheric Chemistry and Physics | Copernicus Publications | Published : 2018


The stratospheric age of air (AoA) is a useful measure of the overall capabilities of a general circulation model (GCM) to simulate stratospheric transport. Previous studies have reported a large spread in the simulation of AoA by GCMs and coupled chemistry–climate models (CCMs). Compared to observational estimates, simulated AoA is mostly too low. Here we attempt to untangle the processes that lead to the AoA differences between the models and between models and observations. AoA is influenced by both mean transport by the residual circulation and two-way mixing; we quantify the effects of these processes using data from the CCM inter-comparison projects CCMVal-2 (Chemistry–Climate Model Va..

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Awarded by Helmholtz Association

Funding Acknowledgements

This study was funded by the Helmholtz Association under grant VH-NG-1014 (Helmholtz-Hochschul-Nachwuchsforschergruppe MACClim). We acknowledge the modeling groups for making their simulations available for this analysis, the WCRP SPARC Chemistry-Climate Model Validation (CCMVal) Activity and the SPARC/IGAC Chemistry-Climate Model Initiative (CCMI) project for organizing and coordinating the model data analysis activity, as well as the British Atmospheric Data Centre (BADC) for collecting and archiving the CCMVal and CCMI model output. Moreover, we want to acknowledge that the EMAC simulations were done within the project ESCiMo (Earth System Chemistry integrated Modelling), a national (German) contribution to the Chemistry-Climate Model Initiative, and have been performed at the German Climate Computing Centre DKRZ through support from the Bundesministerium fur Bildung und Forschung (BMBF). Moreover, we thank Florian Haenel and Gabriele Stiller for providing us the MIPAS AoA data, Marianna Linz for providing us AoA from GOZCARDS N<INF>2</INF>O data and also Andreas Engel for providing us the in situ tropical AoA data.