Multidecadal Changes in the Influence of the Arctic Oscillation on the East Asian Surface Air Temperature in Boreal Winter

Hainan Gong,Lin Wang,Wen Chen

doi:10.3390/atmos10120757

Abstract

The time-varying influences of the wintertime Arctic Oscillation (AO) on the concurrent East Asian surface air temperature (EAT) are investigated based on JRA-55 reanalysis data. Results reveal that there are multidecadal variations in the influences of wintertime AO on the EAT during 1958–2018. Before the mid-1980s, the impact of winter AO on the simultaneous EAT is weak and confined northward of 40° N over East Asia. After the mid-1980s, by contrast, the winter AO’s influence is stronger and can extend southward of 25° N over East Asia. The multidecadal variations of the winter AO–EAT relationship are mainly modulated by the magnitudes of the North Pacific center of the winter AO. During the periods with strong North Pacific center of the winter AO, in association with the positive phase of the winter AO, the low-level southeasterly anomalies on the west side of the anticyclone over North Pacific bring warm air from the ocean to East Asia and lead to a significant winter AO–EAT relationship. In contrast, the southerly anomalies are weak and even reversed to northerly over the coast of East Asia during the periods with weak North Pacific center of winter AO, which confines the influence of winter AO on northern East Asia and lead to an insignificant winter AO–EAT relationship. Our finding provides new insight into the understanding of the decadal changes of AO’s impacts on the regional climate.

Highlights

The Arctic Oscillation (AO) is the leading mode of the extratropical Northern Hemisphere atmospheric circulation variability, and it is most pronounced during boreal winter [1,2]
AO–East Asian surface air temperature (EAT) relationship related to the varied winter AO pattern? The above results suggest that the varied atmospheric circulation anomalies associated with the winter AO over the North Pacific region may contribute to the unstable winter AO–EAT relationship during past decades
Many studies have reported that the winter AO can significantly influence the simultaneous

Summary

Introduction

The Arctic Oscillation (AO) is the leading mode of the extratropical Northern Hemisphere atmospheric circulation variability, and it is most pronounced during boreal winter [1,2]. Jeong and Ho [22] indicated that during the negative phases of winter AO, the Siberian high is strengthened, which may deepen the eastward-moving upper-level shortwave trough aloft over Lake Baikal and facilitate the deepening of the East Asian trough In this situation, the surface anticyclone moves southward, which facilitates the outbreak of cold surge. To date, it is still unclear whether the direct impact the winter AO on the simultaneous East Asian SAT has changed during the past decades.

Data and Methods

Although the SLP winds related to the duringand

Findings

Summary and Discussion