Thermal Expansion in Ocean and Coupled General Circulation Models

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doi: 10.1175/1520-0442(2000)013<1384:TEIOAC>2.0.CO;2 Journal of Climate: Vol. 13, No. 8, pp. 1384–1405. Thermal Expansion in Ocean and Coupled General Circulation Models D. R. Jackett and T. J. McDougall Antarctic CRC, CSIRO Division of Marine Research, Hobart, Tasmania, Australia M. H. England Centre for Environmental Modelling and Prediction, School of Mathematics, University of New South Wales, Sydney, New South Wales, Australia A. C. Hirst CRC for Southern Hemisphere Meteorology, CSIRO Division of Atmospheric Research, Aspendale, Victoria, Australia (Manuscript received 28 September 1998, 11 June 1999)     ABSTRACT     More than half of the predicted rise in future sea level caused by the enhanced greenhouse effect is currently thought to be due to the thermal expansion of the oceans. Here methods for quantifying this thermal expansion component of sea level rise in ocean general circulation models (GCMs) are developed. A simple linear model of ocean heat uptake allows one to find an expression for the future global trend of sea level rise as a function of globally averaged sea surface temperature. The authors also present a robust procedure for obtaining spatial maps of sea level rise in three-dimensional ocean models. The authors then apply these techniques to the ocean components of three runs of the Commonwealth Scientific and Industrial Research Organisation fully coupled GCM. Two of these experiments have been performed with a recent parameterization of oceanic mesoscale eddies. It is shown that this eddy parameterization significantly lowers ocean heat uptake and future sea level rise in ocean GCMs. For the models running with the new eddy parameterization, the simple linear heat uptake model underestimates the sea level rise found in fully coupled GCMs by approximately 10%.