title: Evidence for link between modelled trends in Antarctic sea ice and underestimated westerly wind changes.
abstract: Despite global warming, total Antarctic sea ice coverage increased over 1979-2013. However, the majority of Coupled Model Intercomparison Project phase 5 models simulate a decline. Mechanisms causing this discrepancy have so far remained elusive. Here we show that weaker trends in the intensification of the Southern Hemisphere westerly wind jet simulated by the models may contribute to this disparity. During austral summer, a strengthened jet leads to increased upwelling of cooler subsurface water and strengthened equatorward transport, conducive to increased sea ice. As the majority of models underestimate summer jet trends, this cooling process is underestimated compared with observations and is insufficient to offset warming in the models. Through the sea ice-albedo feedback, models produce a high-latitude surface ocean warming and sea ice decline, contrasting the observed net cooling and sea ice increase. A realistic simulation of observed wind changes may be crucial for reproducing the recent observed sea ice increase.
authors: CSIRO Oceans and Atmosphere, Aspendale, Victoria 3195, Australia.|Climate Change Research Centre, University of New South Wales, Sydney, New South Wales 2052, Australia.|ARC Centre of Excellence for Climate System Science, University of New South Wales, Sydney, New South Wales 2052, Australia.
authors: Ariaan
authors: A
authors: Purich
authors: CSIRO Oceans and Atmosphere, Aspendale, Victoria 3195, Australia.
authors: Wenju
authors: W
authors: Cai
authors: Climate Change Research Centre, University of New South Wales, Sydney, New South Wales 2052, Australia.|ARC Centre of Excellence for Climate System Science, University of New South Wales, Sydney, New South Wales 2052, Australia.
authors: Matthew H
authors: MH
authors: England
authors: CSIRO Oceans and Atmosphere, Aspendale, Victoria 3195, Australia.|School of GeoSciences, University of Edinburgh, Edinburgh EH9 3FE, UK.
authors: Tim
authors: T
authors: Cowan