A distinct sub-seasonal modulation in the Atlantic-originated atmospheric teleconnection influence on East Asian monthly climates

Abstract

The strong sub-seasonal modulation in the atmospheric teleconnection between the North Atlantic and East Asia during boreal winter has been examined. Negative precipitation anomalies and corresponding transient eddy vorticity fluxes over the mid-latitude Atlantic induce a wave packet that leads to cold temperatures over northern China, Korea, and Japan. This relationship is significant for the anomalies averaged from mid-January to mid-February, while it is less for January or February. In mid-January segment, the transient vorticity forcing (TVF) over the mid- to high-latitude Atlantic is the strongest, and consequently, the atmospheric response strengthens the anticyclone over central Eurasia to facilitate strong development of the Siberian High as well as cold temperatures in East Asia. Model simulations support the sub-seasonal linkage modulation through amplitude change of the TVF. It is proposed that intensified atmospheric baroclinicity associated with the deepened North American trough is responsible for the pronounced TVF and downstream influences in mid-January.