A Connection of Winter Eurasian Cold Anomaly to the Modulation of Ural Blocking by ENSO

This study investigates how El Nino-Southern Oscillation (ENSO) modulates winter cold anomalies over central Eurasia (CE) using reanalysis data during 1950-2019. It is found that ENSO can significantly influence winter air temperature over CE mainly through modulating the strength and location of the cyclonic anomaly of Ural blocking (UB) or long-lived UB events. A strong (weak) cyclonic anomaly of UB on the southeastern (eastern) side of the Ural Mountains tends to occur over midlatitude (high-latitude) Eurasia during La Nina (El Nino) winters. Such anomalous circulation leads to a strong (weak) cold anomaly over CE, especially over East Asia, due to enhanced (weakened) cold air advection toward the CE during La Nina (El Nino). The UB-related cyclonic anomaly in the midlatitude (high latitude) side of Eurasia is shown to be related to weakened (enhanced) eastward extension of strong westerly winds over midlatitude Eurasia during La Nina (El Nino) winters.

Automated summary

This study found that ENSO can significantly influence winter air temperature over central Eurasia by modulating the strength and location of the cyclonic anomaly of Ural blocking. Specifically, during La Nina (El Nino) winters, a strong (weak) cyclonic anomaly of Ural blocking on the southeastern (eastern) side of the Ural Mountains leads to a strong (weak) cold anomaly over central Eurasia, especially over East Asia.