On the response of Southern Hemisphere subpolar gyres to climate change in coupled climate models
Article first published online: 7 MAR 2013
©2013. American Geophysical Union. All Rights Reserved.
Journal of Geophysical Research: Oceans
Volume 118, Issue 3, pages 1070–1086, March 2013
How to Cite
2013), On the response of Southern Hemisphere subpolar gyres to climate change in coupled climate models, J. Geophys. Res. Oceans, 118, 1070–1086, doi:10.1002/jgrc.20111.(
- Issue published online: 26 APR 2013
- Article first published online: 7 MAR 2013
- Accepted manuscript online: 13 FEB 2013 07:23AM EST
- Manuscript Accepted: 5 FEB 2013
- Manuscript Revised: 4 FEB 2013
- Manuscript Received: 20 MAR 2012
- Chinese National Key Basic Research Program. Grant Number: 2010CB950301
- China National Natural Science Foundation (NSFC) Project. Grant Number: 41276200
- Special Program for China Meteorology Trade. Grant Number: GYHY201306020
- southern subpolar gyres;
- climate changes;
- coupled climate models
 We investigate the responses of the Southern Hemisphere subpolar gyres to projected climate changes over the 21st century by Coupled Model Intercomparison Project Phase 3 and 5 models. Under increased greenhouse gas forcing, the Southern Hemisphere westerly winds consistently become intensified, resulting in increased cyclonic wind forcing in the subpolar region in these models. Under such wind forcing changes, it is a robust feature that there are consistent increases in the westward flow close to the coast of Antarctica, with strong implications to the mass balance of the Antarctic ice shelves and ice sheets. However, there are large discrepancies in the responses of the gyre axes and overall gyre strengths. Some models show equatorward expansions of the southern gyre limbs, resulting in consistent and large gyre strength increases, while some other models show poleward contractions of the gyres and generally small and less consistent gyre strength changes. These uncertainties are primarily a result of the uncertain simulations of eddy-driven circulations in the Antarctic Circumpolar Current. The associated buoyancy forcing changes play a secondary role in driving these oceanic responses.
This study reveals that there are large uncertainties in the projections of the subpolar circulation in the current generation of coupled climate models, although CMIP5 models have considerably smaller inter-model spreads in the present-day and projected gyre strengths. To predict the subpolar circulation changes, future improved modelling studies need to particularly reduce the uncertainties in the projections of the westerly jet and to reduce the uncertainties in the eddy-driven circulation responses to wind forcing changes.