Abstract
Ocean circulation models based on triangular C-grid discretization are frequently employed to simulate coastal ocean dynamics on unstructured meshes. It is shown that on time and space scales dominated by slow geostrophic dynamics, this discretization tends to exhibit checkerboard noise in the field of horizontal velocity divergence and vertical velocity, respectively. The noise is linked to the geometry of triangular C-grid and is amplified in regimes that are close to geostrophic balance through the particular structure of the Coriolis operator. It can be partly suppressed in some cases but remains a problem in a general case and makes the triangular C-grid a suboptimal choice for large-scale ocean modeling.
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Acknowledgements
I am indebted to E. Hanert and A. Gassmann for their critical remarks on the earlier version of this work which led to substantial changes. The discussion with D. Le Roux was very helpful too.
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Danilov, S. On utility of triangular C-grid type discretization for numerical modeling of large-scale ocean flows. Ocean Dynamics 60, 1361–1369 (2010). https://doi.org/10.1007/s10236-010-0339-6
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DOI: https://doi.org/10.1007/s10236-010-0339-6