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<p>Winter extreme cold days (ECDs) in southern China (SC) have profound socioeconomic impacts on agriculture, energy infrastructure, and public health. This study investigates the distinct atmospheric circulation patterns associated with winter ECDs in SC under El Niño-Southern Oscillation (ENSO) and non-ENSO conditions using high-resolution observational data, reanalysis products, and model outputs spanning 1961–2019. Two fundamentally different dynamical mechanisms govern winter SC ECD occurrence. During ENSO years, SC ECDs are primarily linked to an anomalous cyclonic circulation over the northwestern Pacific, induced by La Niña-related cold sea surface temperature (SST) anomalies, which enhances cold air advection into SC. For non-ENSO years, however, a mid-to-high latitude atmospheric circulation anomaly related to the SC ECD emerges in winter. An intensified subtropical westerly jet stream leads to upper-level divergence, triggering a low-pressure system in the mid-troposphere. This setup enhances the East Asian trough and leads to abnormal cold air intrusion. Our findings emphasize the independent effects of tropical SST forcing and the mid-high latitude circulation system in modulating winter SC ECDs, highlighting critical improvements necessary for seasonal climate predictions and extreme weather risk management.</p>

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Variations of atmospheric circulation anomaly pattern affecting southern China winter extreme low temperature events under ENSO and non-ENSO conditions

  • 期刊论文

  • 发表日期：

    2026年7月2日

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  • Shaogeng Jiang,
  • Chujie Gao,
  • Bo Lu,
  • Hedi Ma,
  • Jinpeng Yuan,
  • Xin Yin,
  • Jiaxuan Liu

摘要

Winter extreme cold days (ECDs) in southern China (SC) have profound socioeconomic impacts on agriculture, energy infrastructure, and public health. This study investigates the distinct atmospheric circulation patterns associated with winter ECDs in SC under El Niño-Southern Oscillation (ENSO) and non-ENSO conditions using high-resolution observational data, reanalysis products, and model outputs spanning 1961–2019. Two fundamentally different dynamical mechanisms govern winter SC ECD occurrence. During ENSO years, SC ECDs are primarily linked to an anomalous cyclonic circulation over the northwestern Pacific, induced by La Niña-related cold sea surface temperature (SST) anomalies, which enhances cold air advection into SC. For non-ENSO years, however, a mid-to-high latitude atmospheric circulation anomaly related to the SC ECD emerges in winter. An intensified subtropical westerly jet stream leads to upper-level divergence, triggering a low-pressure system in the mid-troposphere. This setup enhances the East Asian trough and leads to abnormal cold air intrusion. Our findings emphasize the independent effects of tropical SST forcing and the mid-high latitude circulation system in modulating winter SC ECDs, highlighting critical improvements necessary for seasonal climate predictions and extreme weather risk management.