How slippery are piecewise‐constant coastlines in numerical ocean models?
How slippery are piecewise‐constant coastlines in numerical ocean models?
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DOI：
10.3402/tellusa.v50i1.14514
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
A. Adcroft;D. Marshall
中科院分区：
文献类型：
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作者：
A. Adcroft;D. Marshall
数值海洋模型中的海岸线与模型网格成不同的有限夹角，真实的海岸线通常用分段恒定近似来代替，即模型海岸线与模型网格处处对齐。在这里，我们研究了理想的浅水海洋模型中分段常数近似的结果。通过与物理海岸线成不同的有限角度旋转数值网格，我们能够隔离分段线性边界对模式环流的影响。我们证明，分段恒定的海岸线对模型边界流施加虚假形式的应力，这取决于滑移边界条件的实施和粘性应力传感器的形式。特别是，当采用自由滑移边界条件时，循环的性质可以在分段常数边界存在的情况下简化为无滑移。如果将粘性应力张量写成涡度和散度项，则在自由滑移极限下可以避免纯形式应力。DOI：10.1034/j.1600-0870.1998.00007.x
Coastlines in numerical ocean models are oriented at various finite angles to the model grid.The true coastline is usually replaced by a piecewise-constant approximation in which the modelcoastline is everywhere aligned with the model grid. Here we study the consequences of thepiecewise-constant approximation in an idealised shallow-water ocean model. By rotating thenumerical grid at various finite angles to the physical coastlines, we are able to isolate theimpact of piecewise-linear boundaries on the model circulation. We demonstrate that piecewiseconstantcoastlines exert a spurious form stress on model boundary currents, dependent onboth the implementation of the slip boundary condition and the form of the viscous stresstensor. In particular, when free-slip boundary conditions are applied, the character of thecirculation can be reduced to no-slip in the presence of a piecewise-constant boundary. Thespurious form stress can be avoided in a free-slip limit if the viscous stress tensor is written interms of vorticity and divergence. DOI: 10.1034/j.1600-0870.1998.00007.x