Global Patterns of Diapycnal Mixing from Measurements of the Turbulent Dissipation Rate
Global Patterns of Diapycnal Mixing from Measurements of the Turbulent Dissipation Rate
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DOI：
10.1175/jpo-d-13-0104.1
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发表时间：
2014-07-01
影响因子：
3.5
通讯作者：
Lee, Craig M.
中科院分区：
文献类型：
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作者：
Waterhouse, Amy F.;MacKinnon, Jennifer A.;Lee, Craig M.
作者提出了从5200多个微结构配置文件汇编的diapycnal扩散的推论。由于微观结构观测稀疏，这些都补充了间接测量的混合获得（一）索普尺度翻转从系泊剖面仪，细尺度参数化应用于（二）船上观测上层海洋剪切，（三）应变测量剖面浮标，和（四）剪切和应变从全深度降低声学多普勒海流剖面仪（LADCP）和CTD的配置文件。湍流耗散率的垂直廓线在粗糙的地形和陡峭的孤立脊上底部增强。深度综合耗散率的地理显示出与内波生成相关的空间变异性，这表明湍流有一个直接的能量通道。在1000-m深度以下，全球平均的透环扩散系数为O（10（-4））m（2）s（-1），在1000-m深度以上，全球平均的透环扩散系数为O（10（-5））m（2）s（-1）。编译的微观结构观测样本范围广泛的内部波功率输入和地形粗糙度，提供了一个数据集，估计一个代表性的全球平均耗散率和扩散率。然而，有很强的区域变化之间的比率本地内波的产生和本地耗散。在某些区域，深度积分耗散率与输入到局部内波场的估计功率相当。在少数情况下，更多的内波功率消耗比本地产生的，这表明远程内波源。然而，在大多数位置，通过湍流耗散损失的总功率小于输入到局部内波场中的功率。这意味着在其他地方，如大陆边缘，消散。
The authors present inferences of diapycnal diffusivity from a compilation of over 5200 microstructure profiles. As microstructure observations are sparse, these are supplemented with indirect measurements of mixing obtained from(i) Thorpe-scale overturns from moored profilers, a finescale parameterization applied to (ii) shipboard observations of upper-ocean shear, (iii) strain as measured by profiling floats, and (iv) shear and strain from full-depth lowered acoustic Doppler current profilers (LADCP) and CTD profiles. Vertical profiles of the turbulent dissipation rate are bottom enhanced over rough topography and abrupt, isolated ridges. The geography of depth-integrated dissipation rate shows spatial variability related to internal wave generation, suggesting one direct energy pathway to turbulence. The global-averaged diapycnal diffusivity below 1000-m depth is O(10(-4))m(2) s(-1) and above 1000-m depth is O(10(-5))m(2) s(-1). The compiled microstructure observations sample a wide range of internal wave power inputs and topographic roughness, providing a dataset with which to estimate a representative global-averaged dissipation rate and diffusivity. However, there is strong regional variability in the ratio between local internal wave generation and local dissipation. In some regions, the depth-integrated dissipation rate is comparable to the estimated power input into the local internal wave field. In a few cases, more internal wave power is dissipated than locally generated, suggesting remote internal wave sources. However, at most locations the total power lost through turbulent dissipation is less than the input into the local internal wave field. This suggests dissipation elsewhere, such as continental margins.