Recent research has established a statistical link between North American cold spells (CS) and concurrent wet or windy extremes in Europe. Here, we investigate whether such a link can be related to changes in the characteristics of North Atlantic extratropical cyclones (hereafter cyclones). Despite large regions of anomalous baroclinicity during periods of North American CS, the number of cyclones across the North Atlantic as a whole is not significantly above climatology. However, we observe rates of explosive cyclogenesis significantly above climatology. We further find that CS over different North American regions are associated with large-scale atmospheric configurations displaying a strenghtened jet stream in the vicinity of the CS and different upper-level wind anomalies in the East Atlantic. These, in turn, modulate the regional distributions and characteristics of cyclones in the North Atlantic and Europe. We compute a fixed-radius cyclone footprint which we use to associate extreme precipitation and wind occurrences to individual cyclones. For eastern Canada CS, the North Atlantic jet extends over Northern Europe, resulting in a heightened numbers of cyclones for the British Isles and Scandinavia, while France, the British Isles, Northern Europe and Scandinavia all experience more intense cyclones. The British Isles consistently experience wind extremes associated with cyclones during east Canada CS. For central Canada CS, the jet is displaced poleward and only partly extends over Europe, resulting in an above average cyclone density in the eastern Atlantic and a higher number of cyclones affecting Iberia only. Iberia consistently experiences precipitation extremes associated with the cyclones during central Canada CS. For eastern United States CS, the jet is displaced equatorward and extends over Southern Europe, with a significantly heightened number of cyclones affecting Iberia and France. Iberia experiences wind extremes associated with the cyclones during eastern United States CS. Our results provide a dynamical explanation for previous statistical findings on the concurrence of North American CS and wet or windy extremes over Europe.

最近的研究建立了北美寒潮（CS）与欧洲同时发生的潮湿或多风极端天气之间的统计联系。在这里，我们研究这种联系是否与北大西洋温带气旋（以下简称气旋）特征的变化有关。尽管北美CS期间大片区域出现异常斜压，但整个北大西洋的气旋数量并没有明显高于气候学。然而，我们观察到爆炸性气旋发生率明显高于气候学。我们进一步发现北美不同地区的CS与大规模大气结构有关，C​​S附近显示出增强的急流以及东大西洋不同的高层风异常。这些反过来又调节了北大西洋和欧洲气旋的区域分布和特征。我们计算固定半径的气旋足迹，用于将极端降水和风的发生与各个气旋联系起来。对于加拿大东部，北大西洋急流延伸到北欧，导致不列颠群岛和斯堪的纳维亚半岛的气旋数量增加，而法国、不列颠群岛、北欧和斯堪的纳维亚半岛都经历了更强烈的气旋。在加拿大东部CS期间，不列颠群岛持续经历与气旋相关的极端风力。对于加拿大中部CS，急流向极地移动，仅部分延伸到欧洲上空，导致东大西洋气旋密度高于平均水平，并且仅影响伊比利亚半岛的气旋数量较多。伊比利亚半岛在加拿大中部CS期间持续经历与气旋相关的极端降水。对于美国东部CS，喷气流向赤道移动并延伸到南欧，影响伊比利亚和法国的气旋数量显着增加。伊比利亚半岛在美国东部CS期间经历了与气旋相关的极端风力。我们的结果为之前关于北美CS和欧洲极端潮湿或大风同时发生的统计结果提供了动力学解释。