Comparison of the impact of the Arctic Oscillation and Eurasian teleconnection on interannual variation in East Asian winter temperatures and monsoon

Abstract

The large-scale impacts of the Arctic Oscillation (AO) and the Eurasian teleconnection (EU) on the East Asian winter climate are compared for the past 34 winters, focusing on (1) interannual monthly to seasonal temperature variability, (2) East Asian winter monsoon (EAWM), and (3) the Siberian high (SH) and cold surge. Regression analysis reveals warming by AO and cooling by EU over mid-latitude East Asia during their positive phase and vice versa (i.e., warm phase: +AO, −EU; cold phase: −AO, +EU). The EU impact was found to be comparable to the AO impact. For example, warm (cold) months during the warm (cold) AO phase are found clearly when the AO is in the same warm (cold) EU phase. No significant correlation was found between East Asian temperature and the AO when the warm (cold) AO coincided with the cold (warm) EU. The well-known relationship of strong (weak) SH during the cold (warm) AO phase was observed significantly more often when the AO was in the same cold (warm) EU phase. Also, the indices of EAWM, cold surge, and SH were more highly correlated with the EU than with the AO. The advective temperature change and associated circulation demonstrate that the large-scale field including the SH over the mid-latitude Asian inland is better represented by the EU, influencing the East Asian climate. These results suggest that the impact of EU should be considered more important than previously thought for a better understanding of East Asian winter temperature and monsoon variability.