Responsible: Andreas Jonsson, in collaboration with J. de Grandpré, V. I. Fomichev, J. C. McConnell, and S. R. Beagley (University of Toronto, Canada)
The Canadian Middle Atmosphere Model (CMAM) is a three-dimensional coupled chemistry-climate model (CCM), stretching from the ground to the mesopause. It has a wave driven dynamics, a comprehensive radiation scheme, interactive chemistry, and includes standard tropospheric processes. In collaboration with University of Toronto and York University we have analysed the impact of increases in CO2 mixing ratios on the middle atmosphere. In particular, the photochemical response and radiative feedbacks through ozone changes on the temperature has been investigated.
The results indicate that a doubling of CO2 cools the upper stratosphere and mesosphere by up 10-12 K and induces up to 20% increases in ozone concentrations. Non-interactive simulations show that the temperature response is overestimated by up to 4.5 K when the ozone radiative feedback is not considered. Detailed analyses of the ozone photochemical steady state reveals the most of the ozone response is governed by the temperature dependence of the odd oxygen partitioning reaction O+O2+M -> O3+M. These results have been published and currently the project is being continued by an examination of the impact of changes in sea surface temperatures and sea ice conditions on the upper atmosphere.
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Last updated: January 21, 2006
Jörg Gumbel (gumbel@misu.su.se)