Possible impact of North Atlantic warming on the decadal change in the dominant modes of winter Eurasian snow water equivalent during 1979–2015

Abstract

An east–west dipole mode of winter Eurasian snow water equivalent (SWE) is found during the period of 1979–2015. It accounts for about 23.4% of the total variance, and displayed a significant decadal change in the early-2000s. The basin warming footprint of the North Atlantic likely exerted an influence on this decadal change, and the observation-based evidence is reproduced by numerical experiments using the Community Atmosphere Model (CAM3.1). A basin-wide warming of North Atlantic sea surface temperature induced atmospheric anomalies by exciting a stationary Rossby wave train, which prorogates from the subtropical North Atlantic to the mid-to-high latitudes of the Eurasian continent. Along with the Rossby wave train, an enhanced upper-level ridge occurs over the Ural Mountain, and a deepened upper-level trough appears over the eastern Siberian Plateau, which promotes heavy snowfall over the eastern Siberian Plateau and light snowfall to its west. Thus, it is plausible that the North Atlantic warming plays a role in exciting the Rossby wave train to modulate the decadal change in the east–west dipole SWE mode of the extratropical Eurasian continent. The possible moisture transport paths associated with the decadal change in the east–west dipole SWE mode are also discussed.