Atmospheric circulation impacts on winter maximum sea ice extent in the west Antarctic Peninsula region (1979-2001)

Increasing evidence exists that the strong warming of the West Antarctic Peninsula (WAP) region since the 1950s is related to reduced sea ice that is likely to be due to changes in the atmospheric circulation. Over twenty years of sea ice extent, ice motion and reanalysed near-surface wind data are used to establish that winter ice extent in the West Antarctic Peninsula (WAP) region is largely determined by the meridional (north-south) atmospheric circulation. A remarkably strong ice extent-wind relationship is found in the WAP. No other Antarctic or comparable sub-Arctic sea ice region shows this. Ice motion data confirm wind-induced drift is crucial for extensive winter ice to occur. Reasons for winter ice extent and winds being more strongly correlated in the WAP than in other parts of the Antarctic are discussed along with implications for understanding the observed warming.