Impact of Arctic Sea Ice Interannual Variation on Nonmonsoonal Winter Precipitation over the Eurasian Continent

Abstract

Abstract The present study analyzes the impact of interannual variation in autumn (September–November) Arctic sea ice concentration (SIC) on early winter (November–January) precipitation over nonmonsoonal Eurasian (NME) regions based on both observations and numerical model experiments. An energy budget analysis shows that negative autumn SIC anomalies in the Beaufort–Chukchi–East Siberian Seas (BCES) induce heating in the overlying atmospheric column, which excites a Rossby wave that propagates from the BCES through the Atlantic Ocean to the mid- and high-latitude Eurasian continent. This Rossby wave obtains energy from the mean flow by both baroclinic and barotropic energy conversions. In comparison, the baroclinic energy conversion is more important than the barotropic energy conversion. The low-level anomalous cyclone and anticyclone of the Rossby wave dominate the eastern North Atlantic Ocean–southern Europe and western Russia, respectively. Anomalous westerly wind along the south flank of the anomalous cyclone transports moisture from the North Atlantic Ocean to the continent, resulting in a water vapor flux convergence and positive precipitation anomaly over southern Europe in early winter. Pronounced anomalous northerly winds in the eastern part of the western Russian anticyclone cause negative precipitation anomalies over vast regions of central Asia and the west Siberian plain in early winter. The Rossby wave ray tracing experiment and numerical sensitivity experiments support the above BCES SIC–NME precipitation connection.