Abstract. Variations in the strength of the Northern Hemisphere winter polar stratospheric vortex can influence surface variability in the Atlantic sector. Disruptions of the vortex, known as sudden stratospheric warmings (SSW), are associated with an equatorward shift and deceleration of the North Atlantic jet stream, negative phases of the North Atlantic Oscillation as well as cold snaps over Eurasia and North America. Despite clear influences at the surface on sub-seasonal timescales, how stratospheric vortex variability interacts with ocean circulation on decadal to multi-decadal timescales is less well understood. In this study, we use a 1000-year pre-industrial control simulation of the UK Earth System Model to study such interactions using a wavelet analysis technique to examine non-stationary periodic signals in the vortex and ocean. We find that intervals which exhibit persistent anomalous vortex behaviour lead to oscillatory responses in the Atlantic Meridional Overturning Circulation (AMOC). The origin of these responses appears to be highly non-stationary with spectral power in vortex variability and the AMOC at periods of 30 and 50 years. In contrast, AMOC variations on longer timescales (near 90-year periods) are found to lead to a vortex response, through a pathway involving the equatorial Pacific and Quasi-biennial Oscillation. Using the relationship between persistent vortex behaviour and the AMOC response established in the model, we use a regression analysis to estimate the potential contribution of the 8 year SSW hiatus interval in the 1990s to the recent negative trend in AMOC observations. The result suggests that approximately 30 % of the trend may have been caused by the SSW hiatus.

中文翻译：

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季节性至多年代际时间尺度上平流层极地涡旋与大西洋环流之间的相互作用

摘要。北半球冬季极地平流层涡旋强度的变化会影响大西洋部分的表面变化。涡旋的中断，即平流层突然变暖 (SSW)，与北大西洋急流向赤道移动和减速、北大西洋涛动的负相位以及欧亚大陆和北美的寒流有关。尽管地表对次季节时间尺度有明显影响，但平流层涡旋变化如何与十年至多十年时间尺度上的海洋环流相互作用尚不清楚。在这项研究中，我们使用英国地球系统模型的 1000 年工业控制模拟来研究这种相互作用，使用小波分析技术检查涡旋和海洋中的非平稳周期信号。我们发现表现出持续异常涡行为的间隔导致大西洋经向翻转环流 (AMOC) 的振荡响应。这些响应的起源似乎是高度非平稳的，在 30 年和 50 年的周期内，涡旋变化和 AMOC 的光谱功率是非常不稳定的。相比之下，发现更长时间尺度（近 90 年周期）上的 AMOC 变化会导致涡旋响应，通过涉及赤道太平洋和准双年振荡的路径。利用模型中建立的持续涡行为和 AMOC 响应之间的关系，我们使用回归分析来估计 1990 年代 8 年 SSW 中断间隔对最近 AMOC 观测的负面趋势的潜在贡献。