The observed connection between the Quasi‐Biennial Oscillation and the persistence of the North Atlantic Oscillation in boreal winter
The observed connection between the Quasi‐Biennial Oscillation and the persistence of the North Atlantic Oscillation in boreal winter
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DOI：
10.1002/joc.7769
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发表时间：
2022-06
期刊：
影响因子：
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通讯作者：
Qingyu Cai;Tianjiao Ma;Wen Chen;K. Wei;A. Pogoreltsev;A. Koval
中科院分区：
文献类型：
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作者：
Qingyu Cai;Tianjiao Ma;Wen Chen;K. Wei;A. Pogoreltsev;A. Koval
这项研究表明，北大西洋涛动（NAO）在北半球冬季的持续存在与1958年至2020年期间30 hPa的准两年期涛动（QBO）的位相密切相关。我们的结果表明，初冬（即 11 月至 12 月）NAO 信号往往会持续到随后的 1 月 QBO 东相 (EQBO)。然而，在 QBO (WQBO) 的西风阶段，初冬与随后的 1 月 NAO 信号之间几乎没有联系。进一步分析表明，与WQBO相比，EQBO初冬期间平流层-对流层联系更强，NAO振幅更强。 EQBO 中较强的 NAO 往往会引起海气相互作用的正反馈增强，这可能有助于 NAO 信号的延长。具体而言，由较强的初冬NAO引起的北大西洋高纬度和亚热带地区显着的表面热通量异常可能会在随后的1月份引发北大西洋海面温度异常的三极模式。这种异常海温模式可能对大气产生反馈，通过改变大气斜压和天气涡流活动来增强NAO异常。相比之下，WQBO 初冬的 NAO 往往幅度较弱，并且局限于对流层。研究表明，这种较弱的 NAO 会导致北大西洋的海气相互作用较弱，并且往往不利于 NAO 的延长。
This study reveals that the persistence of North Atlantic Oscillation (NAO) during boreal winter is closely linked to the phase of the Quasi‐Biennial Oscillation (QBO) at 30 hPa for the period 1958–2020. Our results show that the early winter (i.e., November–December) NAO signal tends to persist into the subsequent January in the easterly phase of the QBO (EQBO). However, in the westerly phase of the QBO (WQBO) there is hardly connection between the early winter and the subsequent January NAO signals. Further analysis suggests that there is stronger stratosphere–troposphere connection and stronger amplitude of the NAO during the early winters of the EQBO compared to those of the WQBO. A stronger NAO in the EQBO tends to induce enhanced positive feedback of air–sea interaction, which may contribute to a prolonged signal of the NAO. Specifically, significant surface heat flux anomalies over the high‐latitude and subtropical regions of North Atlantic induced by a stronger early winter NAO may trigger a tripolar pattern of anomalous sea surface temperature in the North Atlantic in the subsequent January. And this anomalous SST pattern may have a feedback on the atmosphere to strength the anomalous NAO by changing the atmospheric baroclinicity and synoptic eddy activities. In contrast, the NAO in the early winters of the WQBO tends to have a weaker amplitude and be confined to the troposphere. This weaker NAO is shown to induce a weaker air–sea interaction in the North Atlantic, and tends not to favour a prolonged NAO.