Interdecadal Variations and Mechanisms of the Seesaw Pattern for Winter Surface Temperature between Northern and Southern Eurasia

The characteristics and mechanism of the spatial and temporal seesaw pattern of winter surface temperature between northern and southern Eurasia was analyzed. Results show that the seesaw pattern of winter surface temperature between northern and southern Eurasia is evident with the boundary located at about 55°N. Besides, the interannual and interdecadal variations of winter surface temperature over Eurasia are also significant during 1961-2015. On the interdecadal scale, planetary waves in the Northern Hemisphere such as the "Three Troughs/Ridges in winter" are closely associated with the seesaw pattern. In addition, this seesaw pattern on the interdecadal scale also has an obvious transitional feature on seasonal scale. Results that exclude the interdecadal and global warming signals indicate that winter surface temperature in Eurasia is significantly correlated with the Arctic sea ice extent in autumn. The decrease in Arctic sea ice extent is one of the main external forcing factors that cause decreases in winter surface temperature in Eurasia, especially in central Asia. Further analysis shows that on interannual time scale, the seesaw pattern has a significant correlation with the synchronous sea surface temperature that displays a "three-pole" structure in the North Atlantic Ocean.