Scholarlink

<p>As global temperatures rise, widespread warming and fewer cold extremes are generally observed. However, using the metric “temperature drop days”, we identify hemispheric divergent trends in winter cold weather over the past four decades. North America experiences increasing temperature drop days, whereas Europe sees a decline, forming a “Cold North America–Warm Europe” pattern. These opposing trends are linked to atmospheric circulation changes: a weakened but asymmetric tropospheric polar vortex has favored more stable circulation over Europe, while a southward-tilting, meandering polar jet enhances daily circulation variability over North America, increasing temperature drop days. Further analysis indicates that this asymmetry primarily arises from tropical Pacific cooling, with contributions from Arctic sea-ice loss, anthropogenic aerosols, and volcanic forcing. In contrast, greenhouse gas forcing mainly drives the overall weakening of the tropospheric polar vortex. Together, this interplay highlights how internal variability and external forcings shape regional winter cold weather.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Hemispheric divergent trends in winter temperature drop days

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2026年4月24日

查看全文
  • Hao Wang,
  • Jianping Li,
  • Fei Zheng,
  • Matthew Collins,
  • Fei Li

摘要

As global temperatures rise, widespread warming and fewer cold extremes are generally observed. However, using the metric “temperature drop days”, we identify hemispheric divergent trends in winter cold weather over the past four decades. North America experiences increasing temperature drop days, whereas Europe sees a decline, forming a “Cold North America–Warm Europe” pattern. These opposing trends are linked to atmospheric circulation changes: a weakened but asymmetric tropospheric polar vortex has favored more stable circulation over Europe, while a southward-tilting, meandering polar jet enhances daily circulation variability over North America, increasing temperature drop days. Further analysis indicates that this asymmetry primarily arises from tropical Pacific cooling, with contributions from Arctic sea-ice loss, anthropogenic aerosols, and volcanic forcing. In contrast, greenhouse gas forcing mainly drives the overall weakening of the tropospheric polar vortex. Together, this interplay highlights how internal variability and external forcings shape regional winter cold weather.