Rapid mixing and exchange of deep-ocean waters in an abyssal boundary current
Rapid mixing and exchange of deep-ocean waters in an abyssal boundary current
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DOI：
10.1073/pnas.1904087116
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发表时间：
2019-07-02
影响因子：
11.1
通讯作者：
Meredith, Michael P.
中科院分区：
文献类型：
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作者：
Garabato, Alberto C. Naveira;Frajka-Williams, Eleanor E.;Meredith, Michael P.
全球海洋的翻转环流主要是由深海混合形成的，深海混合将高纬度下沉的冷沃茨转变为较暖、较浅的沃茨。混合在驱动这种转变的有效性是由两个因素共同决定的：地形附近的湍流强度和混合良好的边界沃茨与分层海洋内部交换的速率。在这里，我们使用的一个主要的翻转环流的分支在南大洋的深海边界流的创新观测，以确定一个以前没有记录的混合机制，通过该机制，深海沃茨有效地通过加强近边界湍流和边界内部交换。该机制的关键是由深海沃茨沿沿着地形边界流动产生的亚中尺度动力学不稳定性。由于有利于这种混合模式的条件是共同的许多深海边界流，我们的研究结果强调了其代表性的海洋翻转模型的必要性。
The overturning circulation of the global ocean is critically shaped by deep-ocean mixing, which transforms cold waters sinking at high latitudes into warmer, shallower waters. The effectiveness of mixing in driving this transformation is jointly set by two factors: the intensity of turbulence near topography and the rate at which well-mixed boundary waters are exchanged with the stratified ocean interior. Here, we use innovative observations of a major branch of the overturning circulation-an abyssal boundary current in the Southern Ocean-to identify a previously undocumented mixing mechanism, by which deep-ocean waters are efficiently laundered through intensified near-boundary turbulence and boundary-interior exchange. The linchpin of the mechanism is the generation of submesoscale dynamical instabilities by the flow of deep-ocean waters along a steep topographic boundary. As the conditions conducive to this mode of mixing are common to many abyssal boundary currents, our findings highlight an imperative for its representation in models of oceanic overturning.