ARCUS 13th Annual Meeting and Arctic Forum 2001

Arctic Sea Ice Oscillation: Regional and Seasonal Perspectives

Jia Wang¹, Moto Ikeda^2
1International Arctic Research Center-Frontier Research Syste, University of Alaska Fairbanks, 930 Koyukuk Dr., Fairbanks, AK, 99775-7335, USA, Phone 907/474-2685, jwang@iarc.uaf.edu
²Graduate School of Environmental Earth Science, Hokkaido University, 060, Japan

Variability of the sea-ice cover (extent) in the Northern Hemisphere (Arctic and subpolar regions) associated with AO (Arctic Oscillation) is investigated using historical data from 1901 to 1997. A principal component analysis (empirical orthogonal functions, EOFs) was applied to sea ice area (SIA) anomalies for the period 1953-95. The leading EOF mode for the SIA anomaly shows an in-phase fluctuation in response to AO and is named ASIO (Arctic sea ice oscillation). Arctic sea ice experiences seasonal variations of different types in timing and magnitude. Four types of seasonal variations are identified in the Arctic sea ice, superimposed on long-term interannual to decadal variability. Consistent with the total Arctic SIA anomaly, eight regional SIA anomalies have shown significant in-phase decrease (downward trend) since 1970, possibly part of a very long-term (century) cycle. Thus, it is recommended that SIA anomalies in the sensitive seasons be used to better capture interannual, interdecadal, and longer (century) variability. Major decadal and interdecadal time scales of SIA anomalies are found 12-14 and 17-20 years. In the Sea of Okhotsk, a century time scale is evident. The reduction rate (negative trend) of the total Arctic sea ice cover in the last three decades is -4.5% per decade with the summer rate being the highest (-10.2% per decade). The contribution to this total reduction varies from region to region, among which sea-ice cover in the Greenland and Norwegian Seas experiences the highest reduction rate of -20.2% per decade.

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