Comparison of Intraseasonal East Asian Winter Cold Temperature Anomalies in Positive and Negative Phases of the Arctic Oscillation

Abstract

This study investigates the relationship between intraseasonal variations of the Arctic Oscillation (AO) and East Asian winter temperature. Based on the lead-lag correlation between 30- and 60-day band-pass filtered daily AO index and regional mean surface temperature anomalies over eastern China, it is found that the cold temperature anomalies occur following both positive and negative AO phases with nearly the same probability. Composite analysis reveals prominent differences in surface temperature and tropospheric circulation anomalies between the two types of years. During the years when negative AO leads cold anomalies over East Asia, the AO-related pressure anomalies extend to Eurasia, inducing an enhanced Siberian high with a large spatial coverage in midlatitude and high latitude; the midtropospheric wave train along the polar front jet takes an eastward path and induces the deepening of the East Asian trough; the resultant cold surface temperature anomalies affect a large region over East Asia. During the years when positive AO leads cold anomalies, the AO-related pressure anomalies extend to North America and the high pressure anomalies over East Asia are located at midlatitudes with a relatively small spatial coverage; the midtropospheric wave train along the polar front jet takes a southward path over Asia, inducing the development of a trough over subtropical Asia with a supplementary contribution from a subtropical wave train; the resultant cold surface temperature anomalies influence inland East Asia with a relatively small extent. There appears to be a notable difference in the relationship between the stratospheric and tropospheric change between the two types of years.