Given the ongoing debate over the link between Arctic warming and mid-latitude cold extremes, the role of Rossby wave propagation emerges as a key aspect warranting investigation. Here, we examine the change in Rossby wave phase speed over Siberia,which has manifested a significant decreasing trend in recent winters and shows a close link with Arctic warming. The low phase speed over the region corresponds to the westward movement of blocking circulation over eastern Siberia, which can result in prolonged cold anomalies over the Eurasian and North American continents. Such a westward-shifting pattern occurs more frequently in the Arctic warming events after the 2000s, accompanied by more persistent cold anomalies over mid-latitude continents. Model simulation further validates the close link between low Siberian phase speed and the cooling over mid-latitude continents, which can be regarded as a forced response to Arctic sea ice loss. These findings imply a new perspective in which the westward movement of Rossby waves over eastern Siberia may serve as a bridge linking Arctic warming and mid-latitude cooling.

Rossby wave