Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 9 1 2009 10.5194/acpd-9-4489-2009 http://www.atmos-chem-phys-discuss.net/9/4489/2009/ http://www.atmos-chem-phys-discuss.net/9/4489/2009/acpd-9-4489-2009.html http://www.atmos-chem-phys-discuss.net/9/4489/2009/acpd-9-4489-2009.pdf 4489 4524 2009-02-23 Impact of prescribed SSTs on climatologies and long-term trends in CCM simulations H. Garny hella.garny@dlr.de M. Dameris A. Stenke Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany Chemistry-Climate Model (CCM) simulations are commonly used to project the past and future development of the dynamics and chemistry of the stratosphere, and in particular the ozone layer. So far, CCMs are usually not interactively coupled to an ocean model, so that sea surface temperatures (SSTs) and sea ice coverage are prescribed in the simulations. While for future integrations SSTs have to be taken from precalculated climate model projections, for CCM experiments resembling the past either modelled or observed SSTs can be used. This study addresses the question to which extent atmospheric climatologies and long-term trends for the recent past simulated in the CCM E39C-A differ when choosing either observed or modelled SSTs. Furthermore, the processes of how the SST signal is communicated to the atmosphere, and in particular to the stratosphere are examined. Two simulations that differ only with respect to the prescribed SSTs and that span years 1960 to 1999 are used. <br><br> Significant differences in temperature and ozone climatologies between the model simulations are found, but long-term trends over 40 years in annual mean temperature and ozone differ only in the troposphere, where temperatures are directly influenced by the local SST trends. 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