Frequency Associations between East Asian Jet Streams and the Temperature over the Barents–Kara Sea Region/Arctic Oscillation in Winter

Wei Song,Yuxiang Zhu,Yuefeng Li

doi:10.3390/cli8100107

Abstract

The frequency associations between jet streams over East Asia and the Arctic key temperature at 2 m (AKT2m) in the Barents–Kara Sea region (40°–75° E, 66°–82° N) and the Arctic Oscillation in winter are investigated using continuous wavelet transform, cross-wavelet transform, and wavelet coherence. The cross-wavelet transforms between the AKT2m/Arctic Oscillation and the East Asian polar front jet stream (EAPJ) suggest that the EAPJ is closely related to the AKT2m and Arctic Oscillation on an interannual (3–5-year band) timescale, but the variation in the phase angle denotes a complex frequency connection between the EAPJ and Arctic Oscillation. The squared wavelet coherence suggests that weakening of the EAPJ is associated with the rise in AKT2m during the period of abrupt climate change in East Asia. The EAPJ contains more forced components from the Arctic than the East Asian subtropical jet stream. By comparison, the relationship between AKT2m and the EAPJ is closer than that between the Arctic Oscillation and EAPJ, especially during the period of abrupt climate change in East Asia. This suggests that the EAPJ serves as a bridge for Arctic warming to affect the weather and climate over East Asia in winter. By contrast, the Arctic Oscillation does not play an important part, although it also contains information about the Arctic.

Highlights

The Arctic has long been regarded as a key region in various climate change scenarios and is synoptically active [1]
We cannot conclude that the East Asian polar front jet stream (EAPJ) can definitely mirror the Arctic Oscillation, there are some phase associations with their significant common power. Their phase connections are complex, possibly due to the overlap of multiple valid variations, and non-linear impact by some factors. These analyses show that the EAPJ contains some forced components from signals in the 3 to 5- and 6 to 10-year bands of the Arctic Oscillation and
AKT2m, the weaker the EAPJ, which is consistent with some previous studies (e.g., [46]). These analyses show the features of the intermittent correlations between the AKT2 and EAPJ, with a close relationship during the period of abrupt climate change in East Asia [in the early 1980s (Hung and Kao [47]); in the mid-1970s (Dai et al [14])]

Summary

Introduction

The Arctic has long been regarded as a key region in various climate change scenarios and is synoptically active [1]. Climate variability can be generated both internally by interactions within or between the individual subcomponents (e.g., the atmosphere, ocean, sea ice, and terrestrial and biological systems) and externally (e.g., volcanic eruptions, variations in solar insolation at the top of the atmosphere, or changes in the atmospheric concentrations of greenhouse gases in response to anthropogenic emissions) [3]. The surface climate of the Northern Hemisphere showed a long-term warming trend in the 20th century, largely caused by anthropogenic forcing but superimposed by natural interdecadal climate variability [3,4]. Polar amplification as a result of meridional heat transport and positive ice-albedo feedback results in more rapid warming at high latitudes than at lower latitudes [5].

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