A Multi-decadal Variability of the Relationship Changes between the Severe Cold in Korea and Siberian High associated with WACE

Abstract:

Since the continental-scale extreme cold winters occurred repeatedly over the Northern Hemisphere in recent decades, many efforts have been made to understand the underlying physical mechanisms. There were attempts to explain the extreme cold with a weakening of baroclinicity in the middle latitudes due to Arctic warming, which is called Warm Arctic-Cold Eurasia (WACE). However, recent studies focused more on internal variability relevant to the issue. This study aims to understand the mechanism of extreme cold in Korea with respect to the internal variability. Using NCEP/NCAR reanalysis data for January, our analysis started from the known relationship between Siberian High (SH) and the winter cold in Korea (K-tas) and found a significant change in the relationship between the periods of 1971-1990 and 1991-2010. The northwestward shift of SH and eastward shift of Aleutian Low appeared to have weakened the role of SH on the winter cold in Korea during the latter period. Using a 15-year low-pass filter and EEMD (Ensemble Empirical Mode Decomposition) analysis, we found that the change in the relationship might have been caused by a multi-decadal variability of WACE with a period of 34.5 years. Our results indicate that the multi-decadal variability of the relationship changes between K-tas and SH can occur by the multi-decadal variability in WACE.

(Acknowledgment) This work was funded by the Korean Meteorological Administration Research and Development Program under Grant KMI (KMI2018-03412). H-J. Shin was also supported by the National Research Foundation of Korea (NRF) and the Center for Women in Science, Engineering and Technology (WISET) Grant (2018-072) funded by the Ministry of Science and ICT (MSIT) under the Program for Returners into R&D.