Interannual Variability of Sea-Ice Cover in the Arctic and Subpolar Regions:
Related to ENSO and NAO?
Jia Wang
International Arctic Research Center, University of Alaska Fairbanks
Fairbanks, Alaska 99775
Tel: 1-907-474-6877
Fax: 1-907-474-7204
jwang@murre.ims.uaf.edu
The nature of the sea-ice cover in the Arctic and the subpolar, regions(Hudson Bay,Baffin Bay and the Labrador Sea) is examined using principal component analysis (of EOF)and sea-ice and atmospheric data from 1953-93.The general temporal and spatial petterns are closely related to NAO(North Atlantic Oscillation)and ENSO (EI Nino-Southern Oscillation) episodes.Particular attention was paid to the three cases of 1972/73, 1982/83,and 1991/92 (also 1997/98 winter in the future) during which the NAO and ENSO ocurred simultaneously.
During the first year of the 1972/73 period, when positive sea surface temperature(SST) anomalies occurred in the eastern tropical Pacific from January 1972 to February 1973 and the Aleutian Low and Icelandic Low substantially depended in winter 1973,there were heavy ice conditions(large sea-ice extents) in the Hudson Bay-Baffin Bay-Labrador region and negative SST anomalies in the Labrador Sea and northwestern North Atlantic Ocean north of 50 degrees, while the most Arctic region was slightly warmer than normal. These conditions are attributed mainly to the coincident large-scale negative surface air temperature (SAT) anomalies in the region. During 1982/83, when the strongest ENSO event of the century occurred, extremely large sea-ice extent anomalies persisted in the Baffin Bay-Labrador Sea region for almost two years. This response was also due in part to negative anomalies on the SAT for much of this period. However, strong northerly winds in the Labrador Sea associated with a deepened Icelandic Low during autumn 1982 and winter 1983 were also a contributing factor. The Arctic region experenced a warmer condition during winter and spring of 1983. During the winter of 1991/92,severe ice conditions were also found off Labrador. Cross-correlations between the regional SAT anomalies and the sea-ice area anomalies, and also the SO and NAO indices for the period 1953-90 provide further support for the above findings. These findings suggest that during the recent 1997/98 ENSO event, the Hudson Bay-Labrador Sea region will experience a heavy ice condition and the most Arctic region will have a warmer condition during the winter and spring of 1998.
