Critical Role of Continental Slopes in Halocline and Eddy Dynamics of the Ekman‐Driven Beaufort Gyre
Critical Role of Continental Slopes in Halocline and Eddy Dynamics of the Ekman‐Driven Beaufort Gyre
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大陆坡在埃克曼驱动的波弗特环流的盐跃层和涡动力学中的关键作用
DOI：
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
P. Isachsen
中科院分区：
文献类型：
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作者：
G. Manucharyan;P. Isachsen
博福特环流（BG）是一个大规模的水深约束环流驱动的表面埃克曼收敛，创造了一个碗状的盐跃层，并存储了很大一部分的北冰洋的淡水。理论研究表明，在环流内部，盐跃层是平衡的Ekman泵和抵消中尺度涡输送激发斜压不稳定之间的平衡。然而，最强的反气旋流发生在陡峭的大陆坡上，尽管已知等深线坡度会影响斜压不稳定性，但它们对BG盐跃层的大规模影响仍未得到探索。在这里，我们使用一个理想化的涡流解决BG模型来证明，大陆坡的存在显着影响的关键环流特征，导致更深的盐跃层，更强的反气旋环流，和长期的平衡。在大陆坡上，由于埃克曼翻转被涡动量驱动的翻转所补偿，欧拉平均环流的幅度急剧减小。涡厚度通量翻转与横向盐输运也减弱了斜坡，表明涡厚度扩散率的减少，尽管等密度线的斜率是最大的。使用理论盐跃层模型，我们表明，它是在大陆坡涡扩散率的本地化减少是至关重要的，在解释盐跃层加深和延长平衡时间。我们的研究结果强调，需要观测研究的涡旋翻转动力学在大陆斜坡和发展的斜坡意识中尺度涡旋参数化低分辨率气候模式。是通过大陆斜坡抵消翻转的埃克曼分量并降低涡流扩散率（斜坡、盐跃层上涡流扩散率的结果），并具有较长的平衡时间尺度
The Beaufort Gyre (BG) is a large-scale bathymetrically constrained circulation driven by a surface Ekman convergence that creates a bowl-shaped halocline and stores a significant portion of the Arctic Ocean's freshwater. Theoretical studies suggest that in the gyre interior, the halocline is equilibrated by a balance between Ekman pumping and counteracting mesoscale eddy transport energized by baroclinic instability. However, the strongest anticyclonic flows occur over steep continental slopes, and, despite bathymetric slopes being known to influence baroclinic instability, their large-scale impacts on BG halocline remain unexplored. Here we use an idealized eddy-resolving BG model to demonstrate that the existence of continental slopes dramatically affects key gyre characteristics leading to deeper halocline, stronger anticyclonic circulation, and prolonged equilibration. Over continental slopes, the magnitude of the Eulerian mean circulation is dramatically reduced due to the Ekman overturning being compensated by the eddy momentum-driven overturning. The eddy thickness flux overturning associated with lateral salt transport is also weakened over the slopes, indicating a reduction of eddy thickness diffusivity despite the isopycnal slopes being largest there. Using a theoretical halocline model, we demonstrate that it is the localized reduction in eddy diffusivity over continental slopes that is critical in explaining the halocline deepening and prolonged equilibration time. Our results emphasize the need for observational studies of eddy overturning dynamics over continental slopes and the development of slope-aware mesoscale eddy parameterizations for low-resolution climate models. are by continental over slopes counteract the Ekman component of the overturning and reduce eddy diffusivity a consequence of eddy diffusivity over slopes, halocline and has a prolonged equilibration timescale
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影响因子：
3.5
作者：
C. Lique;H. Johnson;P. Davis
通讯作者：
C. Lique;H. Johnson;P. Davis
影响因子：
3.5
作者：
Manucharyan, Georgy E.;Thompson, Andrew F.;Spall, Michael A.
通讯作者：
Spall, Michael A.
影响因子：
3.6
作者：
Aksenov, Yevgeny;Ivanov, Vladimir V.;Beszczynska-Moeller, Agnieszka
通讯作者：
Beszczynska-Moeller, Agnieszka
影响因子：
3.6
作者：
Armitage, Thomas W. K.;Bacon, Sheldon;Wingham, Duncan J.
通讯作者：
Wingham, Duncan J.