ACPD Atmospheric Chemistry and Physics Discussions ACPD 1680-7375 Copernicus GmbH Göttingen, Germany 10.5194/acpd-9-4489-2009 Impact of prescribed SSTs on climatologies and long-term trends in CCM simulations Garny H. 1 Dameris M. 1 Stenke A. 1 Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany 23 02 2009 9 1 4489 4524 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.atmos-chem-phys-discuss.net/9/4489/2009/acpd-9-4489-2009.html The full text article is available as a PDF file from http://www.atmos-chem-phys-discuss.net/9/4489/2009/acpd-9-4489-2009.pdf

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. However, differences in trends are found on shorter time scales and the results suggest that these differences in trends are induced by associated SST trends. The SST trends lead to modifications in planetary wave activity and therefore a modulation of the Brewer-Dobson Circulation (BDC). This results in time series of tropical upwelling, as a measure of the strength of the BDC, differing strongly between the simulations. A reverse from negative to positive trends is found in the simulation using observed SSTs while trends are positive throughout the simulation when using modelled SSTs.

 References Andrews, D., Holton, D., and Leovy, C.: Middle Atmosphere Dynamics, Academic Press, San Diego, California, 1987. Bodeker, G E., Garny, H., Smale, D., Dameris, M., and Deckert, R.: The 1985 Southern Hemisphere mid-latitude total column ozone anomaly, Atmos. Chem. Phys., 7, 5625–5637, 2007. Braesicke, P. and Pyle, J.: Sensitivity of dynmaics and ozone to different representations of SSTs in the Unified Model, Q. J. R. Meteorol. Soc., 130, 2033–2045, 2004. Butchart, N., Scaife, A., Bourqui, M., de~Grandpre, J., Hare, S., Kettleborough, J., Langematz, U., Manzini, E., Sassi, F., Shibata, K., Shindell, D., and Sigmond, M.: Simulations of anthropogenic change in the strength of the Brewer-Dobson circulation, Clim. Dynam., 27, 727–741, 2006. Charney, J G. and Drazin, P G.: Propagation of planetary-scale disturbances from the lower into the upper atmosphere, J. Geophys. Res., 66, 83–109, 1961. Dameris, M., Grewe, V., Ponater, M., Deckert, R., Eyring, V., Mager, F., Matthes, S., Schnadt, C., Stenke, A., Steil, B., Brühl, C., and Giorgetta, M.: Long-term changes and variability in a transient simulation with a chemistry-climate model employing realistic forcing, Atmos. Chem. Phys., 5, 2121–2145, 2005. Dameris, M., Matthes, S., Deckert, R., Grewe, V., and Ponater, M.: Solar cycle effect delays onset of ozone recovery, Geophys. Res. Lett., 33, L03806, doi:10.1029/2005GL024741, 2006. Deckert, R. and Dameris, M.: Higher tropical SSTs strengthen the tropical upwelling via deep convection, Geophys. Res. Lett., 35, L10813, doi:10.1029/2008GL033719, 2008a. Deckert, R. and Dameris, M.: From Ocean to Stratosphere, Science, 322, 53–55, 2008b. Edmon, H J., Hoskins, B J., and McIntyre, M E.: Eliassen-Palm cross sections for the troposphere, J. Atmos. Sci., 37, 2600–2616, 1980. Eyring, V., Harris, N R P., Rex, M., Shepherd, T G., Fahey, D W., Amanatidis, G T., Austin, J., Chipperfield, M P., Dameris, M., Forster, P M D F., Gettelman, A., Graf, H F., Nagashima, T., Newman, P A., Pawson, S., Prather, M J., Pyle, J A., Salawitch, R J., Santer, B D., and Waugh, D W.: A Strategy for Process-Oriented Validation of Coupled Chemistry Climate Models., B. Am. Soc., 86, 1117–1133, 2005. Eyring, V., Chipperfield, M., Giorgetta, M., Kinnison, D E., Manzini, E., Matthes, K., Newman, P., Pawson, S., Shepherd, T., and Waugh, D.: Overview of the New CCMVal Reference and Sensitivity Simulations in Support of Upcoming Ozone and Climate Assessments and Planned SPARC CCMVal, SPARC Newsletter, 30, 20–26, 2008. Grewe, V.: The origin of ozone, Atmos. Chem. Phys., 6, 1495–1511, 2006. Haynes, P., Marks, C., McIntyre, M., Shepherd, T., and Shine, K.: On the "downward control" of extratropical diabatic circulations by eddy-induced mean zonal forces, J. Atmos. Sci., 48, 651–678, 1991. Hein, R., Dameris, M., Schnadt, C., Land, C., Grewe, V., Köhler, I., Ponater, M., Sausen, R., Steil, B., Landgraf, J., and Brühl, C.: Results of an interactively coupled atmospheric chemistry- general circulation model: Comparison with observations, Ann. Geophys., 19, 435–457, 2001. Holton, J R.: An introduction to dynamic meteorology, International geophysics series, San Diego, New York: Academic Press, |c2004, 4th ed., 2004. Jiang, X., Eichelberger, S J., Hartmann, D., Shia, R., and Yung, Y.: Influence of Doubled CO<sub>2</sub> on Ozone via Changes in the Brewer-Dobson Circulation, J. Atmos. Sci., 2751–2755, 2007. Johns, T C., Durman, C F., Banks, H T., Roberts, M J., McLaren, A J., Ridley, J K., Senior, C A., Williams, K D., Jones, A., Rickard, G J., Cusack, S., Ingram, W J., Crucifix, M., Sexton, D M H., Joshi, M M., Dong, B.-W., Spencer, H., Hill, R S R., Gregory, J M., Keen, A B., Pardaens, A K., Lowe, J A., Bodas-Salcedo, A., Stark, S., and Searl, Y.: The New Hadley Centre Climate Model (HadGEM1): Evaluation of Coupled Simulations, J. Clim., 19, 1327–1353, 2006. Kushnir, Y., Robinson, W A., Bladé, I., Hall, N M J., Peng, S., and Sutton, R.: Atmospheric GCM Response to Extratropical SST Anomalies: Synthesis and Evaluation, J. Clim., 15, 2233–2256, 2002. Labitzke, K. and collaborators: The Berlin stratospheric data series, Tech. rep., FU Berlin, 2002. Labitzke, K. and Kunze, M.: Stratospheric temperatures over the Arctic: Comparison of three data sets, Meteorologische Zeitschrift, 14, 65–74, 2005. Land, C., Feichter, J., and Sausen, R.: Impact of vertical resolution on the transport of passive tracers in the ECHAM4 model, Tellus B, 54, 344–360, 2002. Li, F., Austin, J., and Wilson, J.: The Strength of the Brewer Dobson Circulation in a Changing Climate: Coupled Chemistry Climate Model Simulations, J. Clim., 21, 40–47, 2008. Manzini, E., Giorgetta, M., Esch, M., Kornblueh, L., and Roeckner, E.: The Influence of Sea Surface Temperatures on the Northern Winter Stratosphere: Ensemble Simulations with the MAECHAM5 Model, J. Clim., 19, 3863–3881, 2006. Martin, G M., Ringer, M A., Pope, V D., Jones, A., Dearden, C., and Hinton, T J.: The Physical Properties of the Atmosphere in the New Hadley Centre Global Environmental Model (HadGEM1). Part I: Model Description and Global Climatology, J. Clim., 19, 1274–1301, 2006. Meehl, G., Covey, C., Delworth, T., Latif, M., McAvaney, B., Mitchell, J., Stouffer, R., and Taylor, K.: THE WCRP CMIP3 Multimodel Dataset: A New Era in Climate Change Research., B. Am. Soc., 88, 1383–1394, 2007. Newman, M.: Interannual to Decadal Predictability of Tropical and North Pacific Sea Surface Temperatures, J. Clim., 20, 2333–2356, 2007. Offermann, D., Jarisch, M., Donner, M., Oberheide, J., Wohltmann, I., Garcia, R., Marsh, D., Naujokat, B., and Winkler, P.: Middle atmosphere summer duration as an indicator of long-term circulation changes, Adv. Space Res., 35, 1416–1422, 2005. Peng, S. and Whitaker, J S.: Mechanisms Determining the Atmospheric Response to Midlatitude SST Anomalies., J. Clim., 12, 1393–1408, 1999. Peng, S., Mysak, L A., Ritchie, H., Derome, J., and Dugas, B.: The Differences between Early and Midwinter Atmospheric Responses to Sea Surface Temperature Anomalies in the Northwest Atlantic., J. Clim., 8, 137–157, 1995. Randel, W J., Garcia, R R., and Wu, F.: Time-Dependent Upwelling in the Tropical Lower Stratosphere Estimated from the Zonal-Mean Momentum Budget., J. Atmos. Sci., 59, 2141–2152, 2002. Rayner, N A., Parker, D E., Horton, E B., Folland, C K., Alexander, L V., Rowell, D P., Kent, E C., and Kaplan, A.: Global Analyses of sea surface temperatures, sea ice, and night marine air temperature since the late nineteenth century, J. Geophys. Res., 108, 4407, doi:10.1029/2002JD002670, 2003. Reithmeier, C. and Sausen, R.: ATTILA: atmospheric tracer transport in a Lagrangian model, Tellus B, 54, 278–299, 2002. Rosenlof, K H. and Reid, G C.: Trends in the temperature and water vapor content of the tropical lower stratosphere: Sea surface connection, J. Geophys. Res., 113, D06107, doi:10.1029/2007JD009109, 2008. Sassi, F., Kinnison, D., Boville, B., Garcia, R., and Roble, R.: Effect of El-Nino Southern Oscillation on the dynamical, thermal and chemical structure of the middle atmosphere, J. Geophys. Res., 109, D17108, doi:10.1029/2003JD004434, 2004. Seidel, D J. and Randel, W J.: Recent widening of the tropical belt: Evidence from tropopause observations, J. Geophys. Res., 112, D20113, doi:10.1029/2007JD008861, 2007. Steil, B., Dameris, M., Brühl, C., Crutzen, P J., Grewe, V., Ponater, M., and Sausen, R.: Development of a chemistry module for GCMs: First results of a multiannual integration, Ann. Geophys., 16, 205–228, 1998. Steinbrecht, W., Haßler, B., Brühl, C., Dameris, M., Giorgetta, M., Grewe, V., Manzini, E., Matthes, S., Schnadt, C., Steil, B., and Winkler, P.: Interannual variation patterns of total ozone and lower stratospheric temperature in observations and model simulations, Atmos. Chem. Phys., 6, 349?374, 2006. Stenke, A., Grewe, V., and Ponater, M.: Lagrangian transport of water vapour and cloud water in the ECHAM4 GCM and its impact on the cold bias, Clim. Dynam., 31, 491–506(16), 2008a. Stenke, A., Dameris, M., Grewe, V., and Garny, H.: Implications of Lagrangian transport for coupled chemistry-climate simulations, Atmos. Chem. Phys. Discuss., 8, 18727–18764, 2008b. Stott, P., Jones, G., Lowe, J., Thorne, P., Durman, C., Johns, T., and Thelen, J.-C.: Transient Climate Simulations with the HadGEM1 Climate Model: Causes of Past Warming and Future Climate Change, J. Clim., 19, 2763–2782, 2006. von Storch, H. and Zwiers, F W.: Statistical Analysis in Climate Research, ISBN 0521012309 Cambridge, UK: Cambridge University Press, March 2002, 2002. WMO: Scientific Assessment of Ozone Depletion: 2006, Tech. rep., WMO Global Ozone Research and Monitoring Project Report No 50, 2007.