How Is Meridional Coherence Maintained in the Lower Limb of the Atlantic Meridional Overturning Circulation?
How Is Meridional Coherence Maintained in the Lower Limb of the Atlantic Meridional Overturning Circulation?
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DOI：
10.1029/2018gl080958
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发表时间：
2019-01
影响因子：
5.2
通讯作者：
Sijia Zou;M. Lozier;M. Buckley
中科院分区：
文献类型：
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作者：
Sijia Zou;M. Lozier;M. Buckley
尽管人们强烈关注大西洋经向翻转环流（AMOC）变异性的纬度连续性，但构成 AMOC 下肢的不同层中的输送连续性受到的关注却相当少。在本研究中，我们研究了北大西洋上层深水 (UNADW) 和北大西洋下层深水 (LNADW) 的运输连通性，两者均由密度定义。使用两个海洋环流模型和海洋再分析，我们发现亚极地起源的输送异常，特别是 UNADW，在 50 年的时间内不会传播到亚热带。我们还发现，两层中的传输都与副极纬度的 AMOC 相关，但只有 LNADW 传输显示与副热带环流中的 AMOC 相关。因此，纬度 AMOC 连续性可能与任何单层的输运连续性无关，而是副极地 AMOC 和副热带 LNADW 输运之间联系的结果。对于强 LNADW 传输事件，这种概括可能存在例外。
Despite a strong focus on latitudinal continuity of the Atlantic Meridional Overturning Circulation (AMOC) variability, transport continuity in different layers that constitute the AMOC lower limb has received considerably less attention. In this study, we investigate the transport connectivity of Upper North Atlantic Deep Water (UNADW) and Lower NADW (LNADW), with both defined by density. Using two ocean circulation models and an ocean reanalysis, we find that subpolar‐originated transport anomalies, particularly for UNADW, do not propagate to the subtropics over a period of five decades. We also find that transports in both layers are linked to AMOC at subpolar latitudes, yet only LNADW transport shows linkage to AMOC in the subtropical gyre. Thus, latitudinal AMOC continuity is likely unrelated to transport continuity in any single layer, but rather a result of connection between subpolar‐AMOC and subtropical‐LNADW transport. An exception to this generalization is possible with strong LNADW transport events.