Articles | Volume 11, issue 2
The Cryosphere, 11, 789–803, 2017
The Cryosphere, 11, 789–803, 2017

Research article 24 Mar 2017

Research article | 24 Mar 2017

Interactions between Antarctic sea ice and large-scale atmospheric modes in CMIP5 models

Serena Schroeter1,2,3, Will Hobbs3,2, and Nathaniel L. Bindoff1,3,2,4 Serena Schroeter et al.
  • 1Institute for Marine and Antarctic Studies (IMAS), 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

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 observations and reanalysis data, and compared with simulated interactions by models in the Coupled Model Intercomparison Project Phase 5 (CMIP5). 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 advance, and it appears that models are able to capture the dominance of the atmosphere during advance. Simulations of ocean–atmosphere–sea ice interactions during retreat, however, require further investigation.

A large proportion of model ensemble members overestimated the relative importance of the Southern Annular Mode (SAM) compared with other modes of 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 zonal patterns of the SAM 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, three of the five 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.

Short summary
Observed trends of Antarctic sea ice are not reproduced by global climate models. We examine observed and simulated interactions between sea ice and large-scale atmospheric variability, showing that global climate models generally capture observed interactions during the season of sea ice advance, but not during sea ice retreat. Most models overestimate the zonally symmetric influence of the dominant atmospheric mode on sea ice, while the importance of tropical variability is underestimated.