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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Decadal deep-water variability in the subtropical Atlantic and convection in the Weddell Sea
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Decadal deep-water variability in the subtropical Atlantic and convection in the Weddell Sea

机译：亚热带大西洋的年代际深水变化和韦德尔海的对流

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This study suggests a link between convection in the Weddell Sea and deepwater flows in the (sub)tropical Atlantic. Employing a global sea ice-ocean general circulation model, events of enhanced convection are found to create enhanced outflow of Antarctic Bottom Water (AABW), the associated anomaly of which propagates rapidly along the model's deep western boundary. The propagation timescale of the order of a few years to reach the tropical Atlantic matches baroclinic Kelvin waves with phase speed corrected for the model's grid resolution. This feature is consistent with earlier findings on the baroclinic adjustment to perturbations of the rate of North Atlantic Deep Water (NADW) formation. The mean deep ocean transports, as well as the timescales and amplitudes of the deep ocean anomalies, are in good agreement with observation-based estimates. Upon arrival in the deep western tropical Atlantic, the model AABW anomalies induce strong anomalies in NADW outflow. This behavior suggests that the actual magnitude of NADW outflow across 30 S is highly susceptible to external perturbations on the baroclinic adjustment timescale. The implied higher susceptibility is supported by recent observations that NADW turns mostly eastward between 20 S and 30 S. The NADW anomalies eventually propagate southward and join the Antarctic Circumpolar Current. There is weak indication that the associated anomalies enter the eastern Weddell Gyre to eventually feed back on the critical convection site in the Weddell Sea, possibly sustaining the oscillation: However, there is stronger evidence that the anomalies initially created by the convective events are advected with the model's Weddell Gyre, the advective timescale of which (10-12 years) is consistent with the periodicity of the convective events. [References: 70]
机译：这项研究表明，韦德尔海的对流与（亚）热带大西洋的深水流动之间存在联系。利用全球海冰海洋总循环模型，发现对流增强的事件导致南极底水（AABW）的流出量增加，其相关异常沿模型深西部边界迅速传播。到达热带大西洋的几年的传播时间尺度与斜压开尔文波相匹配，相速度已针对模型的网格分辨率进行了校正。此功能与早期对斜压调节北大西洋深水（NADW）形成速率的发现相一致。深海平均运输量以及深海异常的时标和幅度与基于观测的估计值非常吻合。到达深部热带西部大西洋后，模型AABW异常在NADW流出中引起强烈异常。此行为表明，在30秒钟内，NADW的实际流出量在斜压调节时标上极易受到外界干扰的影响。最近的观察表明，NADW大多在20 S和30 S之间向东旋转，这暗示了较高的磁化率。NADW异常最终向南传播并加入南极绕极流。几乎没有迹象表明相关的异常进入韦德尔东部涡流，最终反馈到韦德尔海的关键对流点，可能会维持这种振荡：但是，有更强有力的证据表明，对流事件最初造成的异常与该模型的Weddell Gyre，其对流时间尺度（10-12年）与对流事件的周期性一致。 [参考：70]

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