Revealing the Formation of the Dipole Mode of Eurasian Snow Cover Variability During Late Autumn

A zonal dipole pattern of the interannual variability of Eurasian snow cover during late autumn has attracted growing interest due to its extensive influences on large-scale atmospheric circulations and climate anomalies, but it remains unknown what influences the formation of this pattern. This study revealed the potential drivers and the related physical processes of the dipole mode of the snow cover variability during 1979-2018. Results showed that the atmospheric circulation anomalies play a crucial role in forming the dipole mode, which could be further attributed to the influences of the atmospheric teleconnection patterns and the variations of sea surface temperature (SST) and sea ice concentration. Specifically, the anomalous circulations related to the teleconnections of the Eastern Atlantic pattern, East Atlantic-Western Russia pattern, and Scandinavian pattern could lead to the anomalies of air temperature and snowfall that directly shape the variability of snow cover. In addition, a dipole structure of the SST anomalies over the North Atlantic exerts an important effect on the snow cover variability through exciting an eastward propagating Rossby wave train prevailing over Eurasia. Moreover, the snow cover variability is closely linked to the sea ice variations over the Barents Sea that can regulate the anomalous circulations over Eurasia by altering the atmospheric dynamic and thermodynamic conditions. These influencing factors jointly account for about 66% of variances in the dipole mode of snow cover variability, suggesting that our findings can substantially improve the understanding of the Eurasian snow cover variations.