Energetics of Bottom Ekman Layers during Buoyancy Arrest
Energetics of Bottom Ekman Layers during Buoyancy Arrest
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DOI：
10.1175/jpo-d-15-0041.1
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发表时间：
2015-12
影响因子：
3.5
通讯作者：
L. Umlauf;W. Smyth;J. Moum
中科院分区：
文献类型：
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作者：
L. Umlauf;W. Smyth;J. Moum
摘要湍流底埃克曼层是海洋中最重要的能量转换场所之一。它们的能量学是出了名的复杂，特别是在倾斜地形附近，在那里，跨坡的埃克曼输送、浮力强迫和混合之间的反馈以一种尚不清楚的方式影响着能量收支。在这里，作者试图用理论和模型相结合的方法来澄清能量途径和不同的混合途径。该分析是基于一个新开发的斜坡地形附近湍流埃克曼层的能量通量图，该图允许对不同的能量库和能量路径进行精确定义。利用二阶矩湍流模型，表明混合效率随着坡角和内部分层的增加而增加，但不超过5%的阈值，除非非常陡峭的斜坡，在那里可能达到20%的标准值。横坡平流产生的有效势能可达…
AbstractTurbulent bottom Ekman layers are among the most important energy conversion sites in the ocean. Their energetics are notoriously complex, in particular near sloping topography, where the feedback between cross-slope Ekman transports, buoyancy forcing, and mixing affects the energy budget in ways that are not well understood. Here, the authors attempt to clarify the energy pathways and different routes to mixing, using a combined theoretical and modeling approach. The analysis is based on a newly developed energy flux diagram for turbulent Ekman layers near sloping topography that allows for an exact definition of the different energy reservoirs and energy pathways. Using a second-moment turbulence model, it is shown that mixing efficiencies increase for increasing slope angle and interior stratification, but do not exceed the threshold of 5% except for very steep slopes, where the canonical value of 20% may be reached. Available potential energy generated by cross-slope advection may equal up to ...