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<p>Numerous previous studies have suggested that a weak stratospheric polar vortex (SPV) could trigger the occurrence of extreme cold events (ECEs) and the different morphology of SPVs has different influence on tropospheric circulation. However, it is still unclear whether the deformation of moderate SPVs has an influence on the ECEs in China. Using the long-term reanalysis dataset from 1960/1961 to 2022/2023, it is shown that about half of the total ECEs occur under moderate SPV conditions. And extreme cold days in China related to moderate SPVs have become more frequent in the past decade. Further analysis suggested that the moderate SPVs extending toward the Atlantic-Euro region were accompanied by positive potential vorticity (PV) anomalies and the reflection of planetary wave, which amplified the trough over the corresponding region. Moreover, the PV anomalies associated with the moderate SPV extending toward the Atlantic-Euro region show a closer relationship with the trough in the corresponding region since the 1990s. The strengthening of the trough in the Atlantic-Euro region contributes to the amplification of the Ural ridge and the East Asian trough. Consequently, cold air gradually intensified and invaded China. Our findings suggest that moderate SPVs have played an increasingly significant role in ECEs in China in the past decade, which help better understand the stratosphere-troposphere interactions over Asia and provide valuable insights for improving the prediction levels of ECEs in China.</p>

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An increasing role of moderate stratospheric polar vortex in extreme cold events in China in the past decade

  • 期刊论文

  • 发表日期：

    2026年5月28日

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  • Meichen Liu,
  • Dingzhu Hu

摘要

Numerous previous studies have suggested that a weak stratospheric polar vortex (SPV) could trigger the occurrence of extreme cold events (ECEs) and the different morphology of SPVs has different influence on tropospheric circulation. However, it is still unclear whether the deformation of moderate SPVs has an influence on the ECEs in China. Using the long-term reanalysis dataset from 1960/1961 to 2022/2023, it is shown that about half of the total ECEs occur under moderate SPV conditions. And extreme cold days in China related to moderate SPVs have become more frequent in the past decade. Further analysis suggested that the moderate SPVs extending toward the Atlantic-Euro region were accompanied by positive potential vorticity (PV) anomalies and the reflection of planetary wave, which amplified the trough over the corresponding region. Moreover, the PV anomalies associated with the moderate SPV extending toward the Atlantic-Euro region show a closer relationship with the trough in the corresponding region since the 1990s. The strengthening of the trough in the Atlantic-Euro region contributes to the amplification of the Ural ridge and the East Asian trough. Consequently, cold air gradually intensified and invaded China. Our findings suggest that moderate SPVs have played an increasingly significant role in ECEs in China in the past decade, which help better understand the stratosphere-troposphere interactions over Asia and provide valuable insights for improving the prediction levels of ECEs in China.