The Persistent Impact of Winter Arctic Oscillation on the East Asian Surface Air Temperature

A statistical research of NCEP/NCAR reanalysis data and Met Office HadISST over the period of 1948-2013 is conducted to explore the influence of the winter AO on East Asian surface air temperature. The positive phase of the winter AO is characterized by weakened East Asia deep trough as well as Siberian high, low-level southerly wind field, and weakened East Asian winter monsoon resulting in temperature rise. The contrary is the case in the negative phase of the winter AO.In high latitudes, atmospheric variability in winter is very large. With probing deeply into the relationship between monthly winter AO and East Asian surface air temperature, it is found that the impact of AO in January and February can last 2 months or longer, respectively. And the impact will almost disappear in June. The effect of winter AO itself on monthly scale is not consistent. AO can only last no more than two months after self-correlation analysis. But though a large amount of ocean heat content, sea change is slow and persistent. Ocean can store abnormal information of atmosphere, and then acting on atmosphere. For the positive phase of AO, the sea surface temperature (SST) in Western Pacific and East Asian surface temperature are simultaneously abnormally high, and anomalous northeast trades lead to SST anomalies in Western Pacific, making Western Pacific carry AO signals for more than 4 months.With effects of Western Pacific, AO signals are passed continuously into East Asia. Above all, effects of SST in Western Pacific are of vital importance for the persistent impact of Arctic Oscillation on the East Asia through air-sea interaction.