Journal Article

Influence of Major Stratospheric Sudden Warming on the Unprecedented Cold Wave in East Asia in January 2021

Jiang, Dabang, Li, Qingquan, Wang, Guofu, Si, Dong, Ding, Yihui, Zhang, Yingxian

2022

Overview

An unprecedented cold wave intruded into East Asia in early January 2021 and led to record-breaking or historical extreme low temperatures over vast regions. This study shows that a major stratospheric sudden warming (SSW) event at the beginning of January 2021 exerted an important influence on this cold wave. The major SSW event occurred on 2 January 2021 and subsequently led to the displacement of the stratospheric polar vortex to the East Asian side. Moreover, the SSW event induced the stratospheric warming signal to propagate downward to the mid-to-lower troposphere, which not only enhanced the blocking in the Urals–Siberia region and the negative phase of the Arctic Oscillation, but also shifted the tropospheric polar vortex off the pole. The displaced tropospheric polar vortex, Ural blocking, and another downstream blocking ridge over western North America formed a distinct inverted omega-shaped circulation pattern (IOCP) in the East Asia–North Pacific sector. This IOCP was the most direct and impactful atmospheric pattern causing the cold wave in East Asia. The IOCP triggered a meridional cell with an upward branch in East Asia and a downward branch in Siberia. The meridional cell intensified the Siberian high and low-level northerly winds, which also favored the invasion of the cold wave into East Asia. Hence, the SSW event and tropospheric circulations such as the IOCP, negative phase of Arctic Oscillation, Ural blocking, enhanced Siberian high, and eastward propagation of Rossby wave eventually induced the outbreak of an unprecedented cold wave in East Asia in early January 2021.

• Publisher: Science Press,Springer Nature B.V,National Climate Center,China Meteorological Administration,Beijing 100081,China%Climate Change Research Center,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029,China
• Subject: Arctic Oscillation / Atmospheric Sciences / Circulation patterns / Cold / Cold waves / Earth and Environmental Science / Earth Sciences / Extreme cold / Extreme Cold Events from East Asia to North America in Winter 2020/21 / Extreme low temperatures / Geophysics/Geodesy / Historic temperatures / Low temperature / Lower troposphere / Meteorology / Original Paper / Planetary waves / Polar vortex / Rossby waves / Siberian High / Stratosphere / Stratospheric polar vortexes / Stratospheric vortices / Stratospheric warming / Temperature / Troposphere / Ural blocking / Vortices / Wave propagation / Winds