Abstract: By using NCEP/NCAR monthly reanalysis dataset, Arctic Oscillation (AO) indices, the Northern Hemispheric (NH) and its four sectorial polar vortex (PV) area and intensity indices for the period 1951-2012, the relationships between PV, AO and the winter air temperature anomalies over NH continents, especially over Eurasian Continent were investigated. Results indicate that the correlation coefficients between AO index and the winter air temperature over NH showed a “-, +” pattern from the polar region to Eurasian Continent with the most significantly negative correlation center in the polar region and the significantly positive center in the Eurasian mid-high latitudes, but the correlation coefficients between NH’s polar vortex area indices and winter temperatures over NH exhibited a “+, -” pattern. In contrast to the AO index, the significant correlation area between Asian sector polar vortex area indices and winter temperatures expanded southeastward to eastern China, thus revealing some characteristics about the outbreak of the Asian winter monsoon from East Asian mid-high latitudes to the mid-low latitudes. The AO index has shown a decadal decreasing trend whereas both the NH’s and Asian sector polar vortex area indices have exhibited a decadal increasing trend since 2006, this decadal background provided the favorable conditions for the continuous anomalous low winter air temperature over the Eurasian Continent in recent years. The wide range of anomalous low winter air temperature during 2009-2011, was related to the enhancement of the negative phase of AO (except in 2011) and more closely related to the increase of NH’s and Asian sector polar vortex areas. This also indicates that the natural variability of winter cooling was obviously enhanced in Eurasian Continent.

Key words: Eurasian Continent, low temperature in winter, Arctic Oscillation, polar vortex activities, global warming