Together with rapid Arctic warming and sea ice decline, especially over the Barents–Kara seas (BKS), extreme cold winters have occurred frequently in mid-latitudes, particularly in Central Eurasia. A pattern with two distinct winter temperature anomalies centered over the BKS and Central Eurasia is known as the Warm Arctic–Cold Eurasia (WACE) pattern. The impacts of sea ice loss over the BKS and internal atmospheric variability on past WACE formation remain under discussion mainly due to the large internal atmospheric variability in the mid-latitudes. This study analyzed a large-ensemble historical experiment prescribing observed sea ice condition to investigate the role of internal atmospheric variability in the observed interannual variation of the WACE pattern. Comparison of ensemble members suggests that internal atmospheric variability is important for regulating the magnitude of the WACE pattern. Besides the strong effect of local sea ice loss, winter temperature over the BKS increases due to warm advection driven by the Ural blocking and positive phase of the North Atlantic Oscillation. A decrease in winter temperature over Central Eurasia is mainly attributable to the cold advection enhanced by Ural blocking rather than the remote effect of sea ice decline over the BKS. Our study reveals the importance of internal atmospheric variability in elucidating the observed interannual variation of the WACE pattern.

随着北极迅速变暖和海冰减少，尤其是巴伦支海-喀拉海（BKS），中纬度地区（尤其是欧亚大陆中部）经常出现极端寒冷的冬季。具有以 BKS 和欧亚大陆中部为中心的两种不同冬季温度异常的模式被称为暖北极 - 冷欧亚大陆 (WACE) 模式。 BKS海冰损失和内部大气变率对过去WACE形成的影响仍在讨论中，主要是由于中纬度地区内部大气变率较大。本研究分析了规定观测到的海冰状况的大型集合历史实验，以研究内部大气变化在观测到的 WACE 模式年际变化中的作用。集合成员的比较表明，内部大气变化对于调节 WACE 模式的幅度很重要。除了当地海冰消失的强烈影响外，由于乌拉尔阻塞和北大西洋涛动正位相驱动的温暖平流，BKS冬季气温升高。欧亚大陆中部冬季气温下降主要归因于乌拉尔阻塞增强的冷平流，而不是白俄罗斯海冰减少的远程影响。我们的研究揭示了内部大气变化在阐明观测到的 WACE 模式年际变化方面的重要性。