The dominant winter modes of large-scale atmospheric variability in the North Atlantic are the North Atlantic Oscillation (NAO), East Atlantic (EA), and Scandinavian (SCA) patterns. This study examines their multi-decadal variability over the Instrumental Period. We identify stages through which interactions between NAO and both EA and SCA phases alter westerly winds and precipitation anomalies in Europe, which would be overlooked if only NAO phases were considered. Additionally, we show periods where EA becomes the leading mode, likely driven by natural ocean-atmosphere coupling variability, which can enhance climate reconstructions and projections. This study also provides new insights into shifts in NAO action centers. The recent shift (post-1980s) is notably distinct within the Instrumental Period. Unlike previous NAO pattern variations, EA and SCA intensify simultaneously, contributing to an expansion of the Azores High, combined with the Atlantic Ridge and/or Scandinavian Blocking. This results in drier conditions in southern Europe and wetter conditions in the north. The simultaneous intensification of NAO, EA, and SCA supports hypotheses of the Azores High expanding towards Central Europe. While this study does not attribute the shift to global warming, the eastward displacement of the northern NAO center post-1980s suggests some anthropogenic forcing through atmospheric and oceanic warming. We thus propose keeping this issue open, despite recent NAO reconstructions not identifying a singular signal in the latter half of the 20th century.

中文翻译：

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20 世纪初无与伦比的类似 EA 的领先变率模式突出了理解北大西洋气候系统中非平稳性的必要性


北大西洋大尺度大气变率的主要冬季模态是北大西洋涛动 （NAO）、东大西洋 （EA） 和斯堪的纳维亚 （SCA） 模式。本研究考察了它们在工具期内的年代际变化。我们确定了 NAO 与 EA 和 SCA 相位之间的相互作用改变欧洲西风和降水异常的阶段，如果只考虑 NAO 阶段，这些阶段将被忽视。此外，我们展示了 EA 成为主导模式的时期，这可能是由自然海洋-大气耦合变化驱动的，这可以增强气候重建和预测。这项研究还对 NAO 行动中心的变化提供了新的见解。最近的转变（1980 年代后）在工具时期明显不同。与以前的 NAO 模式变化不同，EA 和 SCA 同时增强，导致亚速尔高压的扩张，结合大西洋脊和/或斯堪的纳维亚阻塞。这导致南欧的天气更干燥，而北部的天气更潮湿。NAO、EA 和 SCA 的同时加剧支持了亚速尔群岛高地向中欧扩张的假设。虽然这项研究没有将这种转变归因于全球变暖，但 1980 年代后北部 NAO 中心向东移动表明，大气和海洋变暖是一些人为强迫。因此，我们建议对这个问题保持开放性，尽管最近的 NAO 重建在 20 世纪下半叶没有发现单一信号。