Impact of the "Symmetric Instability of the Computational Kind" at mesoscale- and submesoscale-permitting resolutions
Impact of the "Symmetric Instability of the Computational Kind" at mesoscale- and submesoscale-permitting resolutions
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“计算类型的对称不稳定性”在介尺度和亚介尺度允许分辨率下的影响
DOI：
10.1016/j.ocemod.2017.10.006
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发表时间：
2017
期刊：
影响因子：
3.2
通讯作者：
M. Bell
中科院分区：
文献类型：
--
作者：
N. Ducousso;J. Sommer;J. Molines;M. Bell
NEMO在过去10年中使用的能量守恒和拟能守恒动量平流方案(EEN)存在伪数值不稳定性。这种不稳定被称为计算型对称不稳定(SECK)，它是由矢量不变形式的动量平流的两个分量之间的离散不平衡引起的。Hollingsworth等人已经记录了这种不稳定性的性质和消除方法。(1983)，但病患可能在多大程度上干扰中尺度和亚中尺度允许的分辨率的感兴趣的过程仍不清楚。本文通过比较不同版本的EEN动量平流方案对模型积分的影响，评估了病态影响在真实海洋模式模拟中的作用。调查是在全球中尺度允许分辨率(1/4 °)配置和北大西洋次中尺度允许分辨率(1/60 °)配置下进行的。在这两种分辨率下，不稳定性主要改变了最高能量的气流系统，如赤道急流、西部边界流和相干涡旋。研究发现，病态变化的影响随着模式分辨率的提高而增加，在中尺度允许的分辨率下影响显著，在亚中尺度允许的分辨率下影响显著。通过将平衡运动之间的缓慢能量转移重新定向为虚假的能量转移到内部惯性重力波和耗散，病态被证明扭曲了当前系统的正常功能。我们的结果表明，在过去的10年里，病患很可能在中尺度和更精细的分辨率下具有严重破坏的NEMO解决方案(当与EEN方案一起运行时)。
The energy- and enstrophy-conserving momentum advection scheme (EEN) used over the last 10 years in NEMO is subject to a spurious numerical instability. This instability, referred to as the Symmetric Instability of the Computational Kind (SICK), arises from a discrete imbalance between the two components of the vector-invariant form of momentum advection. The properties and the method for removing this instability have been documented by Hollingsworth et al. (1983), but the extent to which the SICK may interfere with processes of interest at mesoscale- and submesoscale-permitting resolutions is still unkown. In this paper, the impact of the SICK in realistic ocean model simulations is assessed by comparing model integrations with different versions of the EEN momentum advection scheme. Investigations are undertaken with a global mesoscale-permitting resolution (1/4 °) configuration and with a regional North Atlantic Ocean submesoscale-permitting resolution (1/60 °) configuration. At both resolutions, the instability is found to alter primarily the most energetic current systems, such as equatorial jets, western boundary currents and coherent vortices. The impact of the SICK is found to increase with model resolution with a noticeable impact at mesoscale-permitting resolution and a dramatic impact at submesoscale-permitting resolution. The SICK is shown to distort the normal functioning of current systems, by redirecting the slow energy transfer between balanced motions to a spurious energy transfer to internal inertia-gravity waves and to dissipation. Our results indicate that the SICK is likely to have significantly corrupted NEMO solutions (when run with the EEN scheme) at mesocale-permitting and finer resolutions over the last 10 years.
中尺度扰动控制非洲南部的海洋间交换
影响因子：
5.2
作者：
Biastoch;J. R. E. Lutjeharms;C. W. Böning;M. Scheinert
通讯作者：
M. Scheinert