Multi-layer quasi-geostrophic ocean dynamics in Eddy-resolving regimes
Multi-layer quasi-geostrophic ocean dynamics in Eddy-resolving regimes
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涡旋分辨模式下的多层准地转海洋动力学
DOI：
10.1016/j.ocemod.2015.07.018
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发表时间：
2015
期刊：
影响因子：
3.2
通讯作者：
Shevchenko I
中科院分区：
文献类型：
--
作者：
Shevchenko I
本文采用准地转模式对风驱动的海洋环流进行了数值研究，该模式结合了精确统计所需的长时间（200年）、精确表示中尺度涡旋所需的空间分辨率（网格间距小于1km）和更真实流态所需的大雷诺数（Re> 104）。我们通过降低涡动粘性来逐渐增加雷诺数，并分析了大尺度环流、能量学和涡动通量的相应变化，目的是了解随着越来越多的自由度变得动态可用，非线性涡动动力学如何影响大尺度海洋环流。三层和六层配置的模式被认为是为了了解更高的斜压模式的影响。参数敏感性研究表明，随着Re的增加，流场的大部分性质都没有接近渐近线的迹象，但在三层模式中，时间平均流场的性质趋于渐近线，而在六层模式中则没有，这表明在较大Re下，较高的斜压模态在动力学上更为活跃。涡动动能和位能在六层情况下增长较快。涡动强迫（涡动通量散度）的强度随Re的增大而增大。涡旋间位涡通量总体上以北向和向上梯度为主。三层和六层模型的解决方案的比较显示，高斜压模式的西边界流的向东射流延伸的穿透长度和相邻的回流区的强度上的抑制性影响。在大的回流区，人口的涡主要是维持在东移急流的东端，而不是在其中心部分的涡生成。最后，通过研究的解决方案的数值收敛性，我们发现涡粘性和所需的网格分辨率之间的经验依赖性：减半的粘度需要减半的网格间距。
The multi-layer quasi-geostrophic model of the wind-driven ocean gyres is numerically investigated using a combination of long-time runs (200 years) needed for accurate statistics, spatial resolutions (grid interval of less than one kilometer) needed for accurate representation of mesoscale eddies, and large Reynolds number (Re> 104) needed for more realistic flow regimes. We gradually increased the Reynolds number by lowering the eddy viscosity and analysed the corresponding changes of the large-scale circulation, energetics and eddy fluxes, with the goal to understand how the nonlinear eddy dynamics affects the large-scale ocean circulation, as more and more degrees of freedom become dynamically available. Three- and six-layer configurations of the model are considered in order to understand effects of higher baroclinic modes. A parameter sensitivity study is also carried out to show that the explored flow regime is robust.AsReincreases, most properties of the flow show no signs of approaching an asymptote, and the following tendencies are found. The time-mean flow properties tend to an asymptote in the three-layer model but not in the six-layer one, suggesting that higher baroclinic modes are dynamically more active at largerRe. The eddy kinetic and potential energies grow faster in the six-layer case. The intensity of the eddy forcing (eddy flux divergence) increases withRe. The inter-gyre eddy potential vorticity flux is predominantly northward and up-gradient for allRestudied. A comparison of the three- and six-layer model solutions revealed an inhibitory influence of high baroclinic modes on the penetration length of the eastward jet extension of the western boundary currents and on the strength of the adjacent recirculation zones. In large-Reregimes, the population of eddies is mostly sustained by the eddy generation at the eastern end of the eastward jet rather than in its central section. Finally, by studying the numerical convergence of the solutions, we found the empirical dependency between the eddy viscosity and the required grid resolution: halving the viscosity requires halving the grid spacing.
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DOI：
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发表时间：
1997
期刊：
影响因子：
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作者：
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DOI：
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发表时间：
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影响因子：
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DOI：
--
发表时间：
1991
期刊：
影响因子：
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