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

Ye Yang,Naru Xie,Meng Gao

doi:10.3390/atmos10120813

Abstract

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.

Highlights

The teleconnections are usually defined as the simultaneous correlations between the planetaryscale circulation anomalies [1,2]
Western Pacific pattern (WP) is in the positive phase, the pattern is characterized by the dipole-like atmospheric circulation anomalies with a negative active center located on the Okhotsk Sea and another positive one situated around the subtropical western North Pacific [6]
When WP pattern is in positive phase it is notable that positive Tmin anomalies appear over almost the whole of East Asia except southeastern Russia

Summary

Introduction

The teleconnections are usually defined as the simultaneous correlations between the planetaryscale circulation anomalies [1,2]. These patterns could exercise an extensive influence on global weather and climate. There were a large number of studies aimed to explore the formation mechanisms and spatio-temporal variability of teleconnections for the past 30 years [3,4,5]. The Western Pacific pattern (WP) is one of the main teleconnections over the North Pacific. WP is in the positive (negative) phase, the pattern is characterized by the dipole-like atmospheric circulation anomalies with a negative (positive) active center located on the Okhotsk Sea and another positive (negative) one situated around the subtropical western North Pacific [6]. The temperature anomalies above (below) normal conditions are observed over almost all regions of

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