Baroclinic Instability in the Presence of Convection
Baroclinic Instability in the Presence of Convection
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DOI：
10.1175/jpo-d-17-0028.1
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发表时间：
2017-11
影响因子：
3.1
通讯作者：
J. Callies;R. Ferrari
中科院分区：
文献类型：
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作者：
J. Callies;R. Ferrari
斜压混合层不稳定性最近被认为是深冬混合层亚中尺度能量的重要来源。虽然到目前为止的重点是这些不稳定性的平衡动力学，它们发生在并取决于由大气强迫小尺度湍流形成的环境。在这项研究中，理想化的数值模拟，允许斜压不稳定和对流小尺度湍流的发展，简单的控制相对强度。如果对流只是弱强迫的，斜压不稳定抑制层和关闭对流，正如预期的。然而，随着强迫的增加，斜压不稳定性对对流的存在具有显著的弹性。即使不稳定性太弱而不能抑制对流层和关闭对流，不稳定性仍然在对流环境中增长并产生斜压涡旋和锋。这表明，尽管在冬季混合层中的大气强迫小尺度湍流，斜压不稳定性可以持续增长，产生平衡的亚中尺度湍流，并修改上部海洋的整体属性。
Baroclinic mixed-layer instabilities have recently been recognized as an important source of submesoscale energy in deep winter mixed layers. While the focus has so far been on the balanced dynamics of these instabilities, they occur in and depend on an environment shaped by atmospherically forced small-scale turbulence. In this study, idealized numerical simulations are presented that allow the development of both baroclinic instability and convective small-scale turbulence, with simple control over the relative strength. If the convection is only weakly forced, baroclinic instability restratifies the layer and shuts off convection, as expected. With increased forcing, however, it is found that baroclinic instabilities are remarkably resilient to the presence of convection. Even if the instability is too weak to restratify the layer and shut off convection, the instability still grows in the convecting environment and generates baroclinic eddies and fronts. This suggests that despite the vigorous atmospherically forced small-scale turbulence in winter mixed layers, baroclinic instabilities can persistently grow, generate balanced submesoscale turbulence, and modify the bulk properties of the upper ocean.