Interactions between Antarctic sea ice and large-scale atmospheric modes in CMIP5 models
Serena Schroeter1,2,3, Will Hobbs3,2, and Nathaniel L. Bindoff1,3,2,41Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, 7004, Australia 2Australian Research Council Centre of Excellence for Climate System Science (ARCCSS), Hobart, 7004, Australia 3Antarctic Climate and Ecosystems Cooperative Research Centre (ACE CRC), Hobart, 7004, Australia 4CSIRO Oceans and Atmosphere, Hobart, 7004, Australia
Received: 22 Aug 2016 – Accepted for review: 27 Sep 2016 – Discussion started: 04 Oct 2016
Abstract. The response of Antarctic sea ice to large-scale patterns of atmospheric variability varies according to sea ice sector and season. In this study, interannual atmosphere-sea ice interactions were explored using observation-based data and compared with simulated interactions by models in the Coupled Model Intercomparison Project Phase 5. Simulated relationships between atmospheric variability and sea ice variability generally reproduced the observed relationships, though more closely during the season of sea ice advance than the season of sea ice retreat. Atmospheric influence on sea ice is known to be strongest during its advance, with the ocean emerging as a dominant driver of sea ice retreat; therefore, while it appears that models are able to capture the dominance of the atmosphere during advance, simulations of ocean-atmosphere-sea ice interactions during retreat require further investigation. A large proportion of model ensemble members overestimated the relative importance of the Southern Annular Mode compared with other modes on high southern latitude climate, while the influence of tropical forcing was underestimated. This result emerged particularly strongly during the season of sea ice retreat. The amplified zonal patterns of the Southern Annular Mode in many models and its exaggerated influence on sea ice overwhelm the comparatively underestimated meridional influence, suggesting that simulated sea ice variability would become more zonally symmetric as a result. Across the seasons of sea ice advance and retreat, 3 of the 5 sectors did not reveal a strong relationship with a pattern of large-scale atmospheric variability in one or both seasons, indicating that sea ice in these sectors may be influenced more strongly by atmospheric variability unexplained by the major atmospheric modes, or by heat exchange in the ocean.
Schroeter, S., Hobbs, W., and Bindoff, N. L.: Interactions between Antarctic sea ice and large-scale atmospheric modes in CMIP5 models, The Cryosphere Discuss., doi:10.5194/tc-2016-200, in review, 2016.