Arctic oscillation and Arctic sea-ice oscillation



The variability of the sea-ice cover in the Arctic and subpolar regions associated with the Arctic Oscillation (AO) was investigated using historical data from 1901 to 1997. Unrotating principal component analyses (or empirical orthogonal functions, EOFs) were applied to demeaned, normalized sea-level pressure (SLP), surface air temperature (SAT), and sea-ice area (SIA) for the periods 1901–97 and 1953–97. The leading SLP EOF mode is the AO. The leading SIA EOF mode is named the Arctic Sea-Ice Oscillation (ASIO), which accounts for 41% of the total variance for the period of 1901-1995. This dominant ASIO is AO-related; its spatial and temporal patterns are consistent with the leading modes of SLP and SAT, and with the total arctic sea-ice anomalies. The second SIA mode is North Atlantic Oscillation (NAO)-related because sea-ice anomalies in the Labrador Sea region and the Greenland Sea region are out of phase. During the last three decades, the arctic sea ice has significantly decreased, which may be the decreasing phase of long term variations.