Possible Mechanisms of Consecutive Heavy Snowfall over the Korean Peninsula in 2014

Abstract

Despite the recent global warming, the exceptional and irregular severe snowfall events frequently occur during the winter season of a certain year and cause serious socioeconomic losses on the corresponding area such as traffic congestion, damage of the crop cultivation and collapse accident. Improving the prediction of these uneven heavy snow and understanding their occurring mechanism are very important to prevent such damages. In this study, we investigated possible mechanisms of the 2014 heavy snowfall event using high-resolution WRF model and observation data. The results of observational analysis indicated that combined effect of synoptic and regional factors (intensified Siberian High, warm SST anomaly, and intricate topographic effect) resulted in the exceptionally longest severe snowfall occurred on the eastern coast region of Korea. To clarify the cause of the snowfall occurrence, this study intended to reproduce the consecutive heavy snowfall in 2014 and performed numerical sensitivity experiments to regional factors by using a regional climate model. The control experiment realistically simulated heavy snow in 2014 while other experiments simulated relatively small snowfall amount compared with the control experiment. In the sea surface temperature (SST) experiments, the anomalous warm SST in 2014 winter led to cyclonic circulation over the Korean Peninsula and thereby the convergence zone between anti-cyclonic circulation by Siberian High and cyclonic circulation by warm SST anomaly appeared over the eastern coast region. Also, the cyclonic circulation increased moisture transfer from the ocean into the eastern coast region. In the topographic experiments, dynamical lifting by mountain effect enhanced the severe snowfall in Yeong-dong region. The results of numerical experiments suggest that the occurrence of this extraordinary longest heavy snowfall might be increased with rising SST by climate change.