Mechanisms Determining the Variability of Arctic Sea Ice Conditions and Export

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Abstract
In an ocean–sea ice model of the Arctic and the northern North Atlantic driven with 50-yr NCEP–NCAR reanalysis data, no appreciable trend in sea ice volume is found for the period 1948–98. However, rather long subperiods, for example, 1965–95, exhibit a large decline in Arctic sea ice volume. These results and the current data situation make connecting “global warming” to Arctic ice thinning very difficult because the large decadal and multidecadal variability masks any trend. Thermal and wind effects linearly contribute to the total sea ice volume variability. Wind stress forcing significantly contributes to the decadal variability in the Arctic ice volume, affecting both thermodynamic growth and the ice export rate. Ice export events are triggered by enhanced cyclonic wind stress over the eastern Arctic. However, large ice export events depend to a similar degree on the presence of thick ice that is generated in a preceding accumulation phase and do not depend on the local wind conditions around Fram Strait.