Wintertime Arctic Sea Ice Extremes and the Simultaneous Atmospheric Circulation

Abstract

Twenty-five years of Arctic sea ice data have been used in conjunction with data from the lower atmosphere (the surface and 700 mb) to establish some concurrent general circulation relationships. Five January climatologies for both maximum and minimum sea ice areas over the entire north polar cap were first determined. The differences between the two sets of mean atmospheric patterns were then found. The student's t-test was used to establish the statistical significance. The results indicate that the wintertime (January–February) atmospheric circulation in the Pacific tends to be weaker during heavy ice conditions while the differences in the Atlantic are not as significant. These results are compared with GCM (general circulation model) simulations with similar maximum ice conditions. Extremes in Arctic sea ice during January were also examined locally. Although extremes in sea ice between Greenland and northern Europe wore not found to be strongly associated with concurrent atmospheric changes, above-normal sea ice in the Bering Sea and the Davis Strait were found to be strongly associated with simultaneous surface northerly flow locally. The regional analysis also showed that above-normal ice is associated with intensification of the closest major low pressure centers and 700 mb troughs.