Global warming in a coupled climate model including oceanic eddy-induced advection

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GEOPHYSICAL RESEARCH LETTERS, VOL. 23, NO. 23, PAGES 3361–3364, 1996

Global warming in a coupled climate model including oceanic eddy-induced advection

Anthony C. Hirst

CSIRO Division of Atmospheric Research, Aspendale, Australia

Hal B. Gordon

CSIRO Division of Atmospheric Research, Aspendale, Australia

Siobhan P. O’Farrell

CSIRO Division of Atmospheric Research, Aspendale, Australia

Abstract

The Gent and McWilliams (GM) parameterization for large-scale water transport caused by mesoscale oceanic eddies is introduced into the oceanic component of a global coupled ocean-atmosphere model. Parallel simulations with and without the GM scheme are performed to examine the effect of this parameterization on model behavior under constant atmospheric CO2 and on the model response to increasing CO2. The control (constant CO2) runs show substantial differences in the oceanic stratification and extent of convection, similar to differences found previously using uncoupled ocean models. The transient (increasing CO2) runs show moderate differences in the rate of oceanic heat sequestration (less in the GM case), as expected based on passive tracer uptake studies. However, the surface warming is weaker in the GM case, especially over the Southern Ocean, which is contrary to some recent supposition. Reasons for the reduced warming in the GM case are discussed. © American Geophysical Union 1996

Index Terms: 4504 Oceanography: Physical: Air/sea interactions (0312); 3339 Meteorology and Atmospheric Dynamics: Ocean/atmosphere interactions (0312, 4504); 4207 Oceanography: General: Arctic and Antarctic oceanography.