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<p>The surface air temperature (SAT) anomalies in boreal winter have significant impacts on agriculture, transportation, and ecological environment. Utilizing reanalysis and numerical simulations, this study examines the combined impacts of the North Atlantic Oscillation (NAO) and the El Niño–Southern Oscillation (ENSO) on the SAT. It is noted that ENSO typically induces a meridional dipole pattern of SAT anomalies over North America and exerts minimal influence on Eurasia, while the NAO generates significant SAT anomalies across southeastern North America and mid-and-high-latitude Eurasia. However, the combined effects of ENSO and NAO on the SAT exhibit nonlinear characteristics compared to the single-factor impact. For a positive NAO, while a positive ENSO enhances the positive SAT anomalies over Eurasia and shifts the positive SAT anomalies northwestward over North America, a negative ENSO reduces the coverage and intensity of the SAT anomalies. In contrast, for a negative NAO, while a positive ENSO intensifies the negative SAT anomalies over Eurasia and southeastern North America, a negative ENSO diminishes the negative SAT anomalies over North America and central and eastern Siberia. It is through distinct teleconnections that the NAO and ENSO exert combined impacts on the SAT. The NAO influences the SAT over North America and Eurasia mainly through regional anomalous circulations, whereas the ENSO modulate these NAO-induced circulation anomalies by triggering Rossby wave trains propagating poleward. Specifically, the positive ENSO enhances the westerly jet over the North Pacific and increases the wave activity flux towards North America. Subsequently, the Rossby wave train amplifies the SAT anomalies in North America. Meanwhile, the ENSO-induced convection anomalies over the Indo-Pacific generate additional Rossby wave trains propagating poleward. These wave trains lead to a barotropic circulation anomaly over eastern Siberia, which further modulates the NAO-induced circulation and SAT anomalies on the mid-and-high-latitude regions to the east of 60°E. This study highlights the combined impacts of ENSO and NAO on the SAT, revealing the intricate interplay between these two important drivers.</p>

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The combined impacts of NAO and ENSO on the surface air temperature anomalies in boreal winter

  • 期刊论文

  • 发表日期：

    2026年4月3日

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  • Xiaojie Li,
  • Zhiwei Zhu,
  • Xuefeng Liu,
  • Lei Wang,
  • Ying Yang

摘要

The surface air temperature (SAT) anomalies in boreal winter have significant impacts on agriculture, transportation, and ecological environment. Utilizing reanalysis and numerical simulations, this study examines the combined impacts of the North Atlantic Oscillation (NAO) and the El Niño–Southern Oscillation (ENSO) on the SAT. It is noted that ENSO typically induces a meridional dipole pattern of SAT anomalies over North America and exerts minimal influence on Eurasia, while the NAO generates significant SAT anomalies across southeastern North America and mid-and-high-latitude Eurasia. However, the combined effects of ENSO and NAO on the SAT exhibit nonlinear characteristics compared to the single-factor impact. For a positive NAO, while a positive ENSO enhances the positive SAT anomalies over Eurasia and shifts the positive SAT anomalies northwestward over North America, a negative ENSO reduces the coverage and intensity of the SAT anomalies. In contrast, for a negative NAO, while a positive ENSO intensifies the negative SAT anomalies over Eurasia and southeastern North America, a negative ENSO diminishes the negative SAT anomalies over North America and central and eastern Siberia. It is through distinct teleconnections that the NAO and ENSO exert combined impacts on the SAT. The NAO influences the SAT over North America and Eurasia mainly through regional anomalous circulations, whereas the ENSO modulate these NAO-induced circulation anomalies by triggering Rossby wave trains propagating poleward. Specifically, the positive ENSO enhances the westerly jet over the North Pacific and increases the wave activity flux towards North America. Subsequently, the Rossby wave train amplifies the SAT anomalies in North America. Meanwhile, the ENSO-induced convection anomalies over the Indo-Pacific generate additional Rossby wave trains propagating poleward. These wave trains lead to a barotropic circulation anomaly over eastern Siberia, which further modulates the NAO-induced circulation and SAT anomalies on the mid-and-high-latitude regions to the east of 60°E. This study highlights the combined impacts of ENSO and NAO on the SAT, revealing the intricate interplay between these two important drivers.