Month‐to‐Month Variations in the Influence of the January Stratospheric Polar Vortex on Late‐Winter Eurasian Surface Air Temperatures

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This study investigated the month‐to‐month variations in the influence of the January stratospheric polar vortex (SPV) on late‐winter Eurasian surface air temperatures (SAT) during 1979–2024. Results revealed that a strong (weak) January SPV leads to sustained warm (cold) anomalies over Eurasian mid‐high latitudes during January–March. Further analysis indicated that the January SPV‐Eurasian SAT relationship is associated with distinct month‐dependent tropospheric circulation pathways, characterized primarily by the Arctic Oscillation (AO) in January, the North Atlantic Oscillation (NAO) in February and the Western Pacific (WP) pattern in March. Specifically, in January, a strong (weak) SPV is linked to a positive (negative) AO phase through the downward propagation of stratospheric circulation anomalies into the troposphere. The SPV‐related and AO‐related circulation anomalies persist into February and evolve into an NAO‐like pattern over the North Atlantic, which contributes substantially to Eurasian SAT anomalies. By March, the January SPV‐related circulation response further evolves into a WP‐like pattern, with its development reinforced by the eastward propagation of AO‐related Rossby waves and the North Pacific SST anomalies, thereby influencing SAT over the mid–high latitudes of Eurasia. Our results suggest that the surface responses associated with January SPV anomalies are mediated by physically coherent, month‐dependent tropospheric teleconnection pathways.