Interactions between the stratospheric polar vortex and Atlantic circulation on seasonal to multi-decadal timescales
Interactions between the stratospheric polar vortex and Atlantic circulation on seasonal to multi-decadal timescales
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DOI：
10.5194/acp-2021-688
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发表时间：
2021-09
影响因子：
6.3
通讯作者：
O. Dimdore-Miles;L. Gray;S. Osprey;J. Robson;R. Sutton;B. Sinha
中科院分区：
文献类型：
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作者：
O. Dimdore-Miles;L. Gray;S. Osprey;J. Robson;R. Sutton;B. Sinha
抽象。北方冬季极地平流层涡旋强度的变化可以影响大西洋地区的地面变化。涡旋的破坏，被称为平流层突然变暖（SSW），与北大西洋急流的向赤道移动和减速，北大西洋涛动的负相以及欧亚大陆和北美的寒流有关。尽管表面对亚季节时间尺度有明显的影响，但平流层涡旋变化如何在十年到多十年时间尺度上与海洋环流相互作用还不太清楚。在这项研究中，我们使用了1000年前的英国地球系统模型的工业控制模拟研究这种相互作用，使用小波分析技术来研究非平稳周期信号的漩涡和海洋。我们发现，间隔表现出持续的异常涡行为导致振荡的大西洋经向翻转环流（AMOC）的响应。这些响应的起源似乎是高度非平稳的涡旋变率和AMOC在30年和50年的周期谱功率。与此相反，AMOC的变化在较长的时间尺度（近90年的周期）被发现，导致涡旋响应，通过一个途径，涉及赤道太平洋和准两年振荡。使用持续的涡旋行为和AMOC响应之间的关系建立在模型中，我们使用回归分析来估计的潜在贡献的8年SSW中断间隔在20世纪90年代的AMOC观测最近的负面趋势。结果表明，大约30%的趋势可能是由SSW中断引起的。
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.