Zonal shift in the cold airmass stream of the East Asian winter monsoon

The East Asian winter monsoon (EAWM) exhibits long-term variations in intensity and spatial pattern, though the latter one is less understood. To investigate the long-term spatial variations of the EAWM and their possible causes, we propose a new position index of the EAWM by quantifying the low-lev...

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Bibliographic Details
Published in:Environmental Research Letters
Main Authors: Qian Liu, Guixing Chen
Format: Article in Journal/Newspaper
Language:English
Published: IOP Publishing 2021
Subjects:
East Asian winter monsoon
cold airmass
position index
zonal shift
long-term variation
atmospheric teleconnection
Environmental technology. Sanitary engineering
TD1-1066
Environmental sciences
GE1-350
Science
Q
Physics
QC1-999
Bering Sea
Pacific
North Atlantic
North Atlantic oscillation
Siberia
Online Access:https://doi.org/10.1088/1748-9326/ac36f5
https://doaj.org/article/a2bc2a6b28ff434396522af61e3fa1db
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Summary:The East Asian winter monsoon (EAWM) exhibits long-term variations in intensity and spatial pattern, though the latter one is less understood. To investigate the long-term spatial variations of the EAWM and their possible causes, we propose a new position index of the EAWM by quantifying the low-level East Asian stream (EAS) of cold airmass in the Lagrangian sense. Based on the new-defined index, we find that the EAS undergoes an evident zonal shift between two channels over the land and coast. At interdecadal timescale, the peak location of the EAS is displaced eastward, with an increasing southward cold airmass flux at the coast since the mid-1960s. The interannual shift of the EAS presents not only the zonal oscillation of peak location between two channels but also the width changes of coastal channel over the northwestern Pacific. These shifts in the EAS are related to the strength changes of two source cold airmass streams from Siberia or Bering Sea, which are associated with the phase changes in the upper-tropospheric atmospheric teleconnections. At interdecadal timescale, the phase change in the North Atlantic Oscillation modulates the zonal shift in the EAS via the East Atlantic-West Russia teleconnection. At interannual timescale, the Pacific/North American teleconnection becomes the dominant factor altering the zonal shift and width change of the EAS.

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