Surface climate response associated with SAM changes

CARRIL A. F. AND C. G. MENÉNDEZ

Honolulu, Hawaii

Workshop; Workshop on Analyses of Climate Model Simulations for the IPCC AR4; 2005

We attempt to extract an average picture ofthe response of the Southern Annular Mode (SAM) toincreasing greenhouse gases (GHG) forcing from amultimodel ensemble of simulations conducted in theframework of the IPCC 4th assessment experiments. Ouranalysis confirms that the climate change signal in the midtohigh southern latitudes projects strongly into the positivephase (PP) of the SAM. Over the present climate time slice(1970–1999), multimodel ensemble mean reproduce theregional warming around the Antarctic Peninsula (AP)associated with the SAM. When increasing GHG (futuretime slice, 2070–2099), warming in the neighborhoodsof the AP and decreasing sea-ice volume in the sea-iceedge region in the Amundsen and Weddell Seasintensifies, suggesting that recent observed sea-icetrends around AP could be associated to anthropogenicforcings. Changes in surface temperature and sea-ice areconsistent with anomalous atmospheric heat transportassociated with circulation anomalies.