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Modeling the Southern Annular Mode Antarctic SAT Connection

Paper Reviewed
Marshall, G.J. and Bracegirdle, T.J. 2015. An examination of the relationship between the Southern Annular Mode and Antarctic surface air temperatures in the CMIP5 historical runs. Climate Dynamics 45: 1513-1535.

Noting that "strong relationships exist between the Southern Annular Mode (SAM) and surface air temperature (SAT) across much of Antarctica," Marshall and Bracegirdle (2015) state that "changes in the SAM will have a profound influence on future Antarctic climate" and that "it is important that the models used to predict climate change can accurately reproduce current SAM-SAT relationships." Thus, they set about to "examine data from 184 historical runs from 50 CMIP5 AOGCMs over the 1961-2005 period to assess how well they reproduce the observed mean and variability of annual and seasonal SAM-SAT relationships at six Antarctic stations."

This work revealed, in the words of the two British Antarctic Survey scientists, that the studied models are (1) "generally unable to replicate existing seasonal cycles in the strength of the SAM-SAT relationship" and that they (2,3) "show much less spatial and especially temporal variability in the strength of these relationships than is observed." In addition, they say that (4) "the CMIP5 models are particularly poor in summer," when (5) "none have SAM-SAT correlation mean variability as large as that observed at Esperanza, Vernadsky and Halley, located in the Antarctic Peninsula/Weddell Sea region." And in light of these findings, they were forced to conclude that "overall the CMIP5 AOGCMs are relatively poor at reproducing current SAM/SAT relationships across Antarctica."

Posted 14 December 2015