Contributions of greenhouse gas forcing and the Southern Annular Mode to historical Southern Ocean surface temperature trends

Kostov, Y., Ferreira, D. ORCID: https://orcid.org/0000-0003-3243-9774, Marshall, J. and Armour, K. (2018) Contributions of greenhouse gas forcing and the Southern Annular Mode to historical Southern Ocean surface temperature trends. Geophysical Research Letters, 45 (2). pp. 1086-1097. ISSN 0094-8276 doi: 10.1002/2017GL074964

Abstract/Summary

We examine the 1979-2014 Southern Ocean (SO) sea surface temperature (SST) trends simulated in an ensemble of coupled general circulation models and evaluate possible causes of the models’ inability to reproduce the observed 1979-2014 SO cooling. For each model we estimate the response of SO SST to step changes in greenhouse gas (GHG) forcing and in the seasonal indices of the Southern Annular Mode (SAM). Using these step-response functions, we skillfully reconstruct the models’ 1979-2014 SO SST trends. Consistent with the seasonal signature of the Antarctic ozone hole and the seasonality of SO stratification, the summer and fall SAM exert a large impact on the simulated SO SST trends. We further identify conditions that favor multidecadal SO cooling: 1) a weak SO warming response to GHG forcing; 2) a strong multidecadal SO cooling response to a positive SAM trend; 3) a historical SAM trend as strong as in observations.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/74921
Identification Number/DOI	10.1002/2017GL074964
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
Publisher	American Geophysical Union
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