Teleconnection processes linking snow cover variability over western Siberia to enhanced early-winter cold waves in South Korea

Abstract. This study examines thermodynamic teleconnection processes to identify the drivers of the increasing frequency of December cold waves in South Korea over the past 46 years. The identified teleconnection is associated with land–atmosphere interactions triggered by reduced October snow cover (SC) over western Siberia. By refining the cold wave advisory criteria of Korea Meteorological Administration, we calculated cold day frequencies. We applied k-means clustering and principal component analysis to extract dominant time series representing nationwide cold day variability. Analyses based on automated synoptic observing system and ERA5 reanalysis data revealed that October SC reduction over western Siberia initiates a positive snow–ice albedo feedback, leading to enhanced surface solar radiation absorption and increased turbulent heat fluxes. These thermodynamic anomalies lead to atmospheric thermal expansion during October through December, thereby strengthening a December anticyclonic anomaly centered over western Siberia. The intensified northerly winds along the eastern flank of this anomaly established a teleconnection pattern that amplifies early-winter cold waves in South Korea. Overall, these results indicate that October SC may serve as a critical precursor to the recent intensification of early-winter cold waves, providing a scientific foundation for policies to adapt and mitigate the socioeconomic impacts of climate change.