Warm Arctic–Cold Eurasia (WACE) Trend: Inference from Large Ensemble Model Simulations

Abstract Concurrent with global warming, the Eurasian continent has experienced frequent cold winters in recent decades. Although still debatable, such Eurasian winter cooling, which was particularly pronounced in the late twentieth century, has been attributed to internal climate variability, the process of which remains elusive. By examining multimodel large ensemble simulations, this study explores the potential sources of internal climate variability responsible for the Eurasian winter cooling trend over 1987–2006. Model simulations show a large ensemble spread in the Eurasian winter temperature trend with an ensemble mean close to zero. A comparison of the ensemble members shows that a circulation pattern favorable for the Eurasian cooling is characterized by the anticyclonic and cyclonic enhancements of sea level pressure (SLP) trend in the subarctic and Aleutian regions, respectiv…