Increased Interannual Variability of March Snowfall in Northeast China after the Late 1990s and Its Relationship with the East Siberian–Chukchi Sea Ice

Northeast China is a region characterized by frequent and concentrated snowfalls, with one of the peaks occurring in March. Given profound impacts of snowfall on natural systems and social economies, understanding the snowfall variability in this region is of great value. This study documents a notable increase in the intensity of interannual variability (IIV) in March snowfall over Northeast China after the late 1990s, with the IIV during 1997–2021 doubling that of the period 1972–1996. This increase in the snowfall IIV is associated with the enhancement of a barotropic anomalous cyclones over the mid–high latitude Asian continent. Furthermore, the relationship of snowfall variability with the sea ice in the East Siberian–Chukchi Seas shifts from a weak to a significant negative correlation. During 1997–2021, associated with the sea ice reduction in the East Siberian–Chukchi Seas during March, anomalous anticyclones dominated the troposphere of the North Pacific, accompanied by barotropic cyclonic anomalies prevailing over mid–high latitude Asia. The barotropic cyclonic anomalies facilitated a southward displacement of the East Asian polar front jet and a westward shift of the East Asian trough, as well as the convergence of anomalous westerlies and southerlies in the lower troposphere of Northeast China. These conditions favor the interactions of cold airs with moist air flows, leading to an increase in snowfall over Northeast China. In contrast, during 1972–1996, the sea ice-related atmospheric circulation anomalies over the North Pacific were weaker and located northeastward. As a result, their coupling with the Asian atmospheric circulations was reduced, thereby weakening the connection of sea ice with the snowfall variability in Northeast China. Further investigation suggests that the intensification of the interaction between the East Siberian–Chukchi Sea ice and the North Pacific atmospheric circulations may be attributed to the climatological change of the North Pacific storm track.