Impact of the November Eurasian teleconnection on the following January Arctic Oscillation

Using observations and model simulations, the impact of the November Eurasian (EU) teleconnection on the following January Arctic Oscillation (Arctic Oscillation) and the possible mechanisms are investigated in this study.        We found that the positive (negative) phase of the November EU pattern favors the negative (positive) phase of AO during the subsequent January, and both the stratosphere-troposphere interactionsand the tropospheric Blocking High (BH) activity anomalies over the Euro-Atlantic sector play an important role in their connections. When the EU pattern is positive (negative) phase in November, the increased (decreased) vertical wave activity over Eurasia and North Atlantic gradually weakens (enhances) the Stratospheric polar vortex (SPV)from November to the following early January, which is then conducive to a downward propagation of positive height anomalies from the stratosphere to troposphere. On the other hand, due to the persistent stronger (weaker) and southward (northward) shifted storm tracks over the Euro-Atlantic sector from November to the following early January, the BH activities over this region are significantly decreased (increased) during the same period, whichthen contributesto positive (negative) height anomalies over the Arctic via the propagation of a zonal wave number 1-3. As both the SPVand BHanomalies over the Euro-Atlantic sector reach the maximum around the late December-early January, the resultant equivalent barotropic AO dipole patterndevelops and finally establishes during the following January.These results are useful for the predictability of the middle winter climate