Yin Manman, Yang Xiu-Qun, Sun Linyuan, Tao Lingfeng, Keenlyside Noel
China Meteorological Administration Key Laboratory for Climate Prediction Studies, School of Atmospheric Sciences, Nanjing University, Nanjing 210023, China.
College of Atmospheric Sciences, Nanjing University of Information Science and Technology, Nanjing, China.
Sci Adv. 2025 Mar 21;11(12):eadr6336. doi: 10.1126/sciadv.adr6336. Epub 2025 Mar 19.
The amplified wintertime Arctic warming has accelerated in recent decades. However, whether and how the warming can cause Eurasian cooling remains debated. By identifying daily Arctic warming events, we find direct observational evidence that the Arctic warming tends to cause substantial Eurasian cooling and an increase in occurrence frequency of Eurasian cooling events with a roughly 2-day lag. We propose a mechanism explaining the causality. We find that the Arctic warming causes a large suppression in activities of daily weather disturbances (referred to as synoptic eddies) over high-latitude Eurasia. This produces a meridional dipole in geopotential height anomalies characterized by an equivalent-barotropic anomalous low (high) and a lower-level cooling (warming) over mid-latitude Eurasia (the Arctic) via a nonlinear eddy-to-mean flow feedback. The feedback induces near-surface northeasterly anomalies that enlarge the Eurasian cooling via cold advection. Thus, we conclude that the warm Arctic versus cold Eurasia is essentially an intrinsic dipole determined by synoptic eddy-mean flow interaction.
近几十年来，冬季北极加速变暖。然而，这种变暖是否以及如何导致欧亚大陆变冷仍存在争议。通过识别每日北极变暖事件，我们发现了直接的观测证据，表明北极变暖往往会导致欧亚大陆大幅降温，并使欧亚大陆降温事件的发生频率增加，且大约有两天的滞后。我们提出了一种解释因果关系的机制。我们发现，北极变暖导致高纬度欧亚大陆上每日天气扰动（称为天气尺度涡旋）的活动大幅受到抑制。这通过非线性涡旋-平均流反馈，在位势高度异常中产生一个经向偶极子，其特征是在中纬度欧亚大陆（北极）上空出现一个相当正压的异常低压（高压）以及低层降温（升温）。这种反馈引发近地表东北风异常，通过冷平流扩大了欧亚大陆的降温。因此，我们得出结论，北极暖而欧亚大陆冷本质上是由天气尺度涡旋-平均流相互作用决定的一种内在偶极子现象。
