Sea Ice Extent and Concentration

During 2011, zonally-averaged Antarctic sea ice extent was characterized by three broad phases that were closely associated with the changes in largescale patterns of atmospheric circulation described in section 6b. From near-average levels at the beginning of the year (compared to the 1981–2010 mean), the zonallyaveraged sea ice extent tracked at 1–2 standard deviations below the long-term mean from mid-January through mid-May (Fig. 6.8a) - including some brief times when it dipped below the 30-year record.