The Relationship between the Wintertime Cold Extremes over East Asia with Large-Scale Atmospheric and Oceanic Teleconnections

The influence of large-scale teleconnection patterns, Western Pacific (WP), Arctic Oscillation (AO) and El Niño-Southern Oscillation (ENSO), on the minimum surface air temperature (Tmin) anomalies and extremes over East Asia during the boreal winter from 1979 to 2017 were investigated by the composite analysis in terms of atmospheric and oceanic processes. The relationship between the Tmin and the geopotential height at 500 hPa (Z500) as well as sea surface temperature (SST) were first examined. Then we explored and estimated the contribution of the teleconnection patterns to the occurrence of extremely cold days and months quantitatively, and discussed other key factors in relation to the cold extremes. The WP and AO patterns play an important part in the prevalence of significant Tmin variability, whereas the effect of ENSO is relatively weak. Most of the cold extremes tend to appear in the negative phase of teleconnections, while there some extremes that occur in the opposite phase. In addition, the extreme months are more related to the preferred phase of the dominant pattern when compared to days. We conclude that the daily extremes are primarily triggered by the local-synoptic atmospheric circulations embedded in the large-scale teleconnection patterns, while the monthly extremes have a closer relationship with these low-frequency patterns.