We present a neutral diffusion operator appropriate for an ocean model making use of general vertical coordinates. The diffusion scheme uses polynomial reconstructions in the vertical, along with a horizontally local but vertically nonlocal stencil for estimates of tracer fluxes. These fluxes are calculated on a vertical grid that is the superset of model columns in a neutral density space. Using flux‐limiters, the algorithm dissipates tracer extrema locally, and no new extrema are created. A demonstration using a linear equation of state in an idealized configuration shows that the algorithm is perfectly neutral. When using the nonlinear TEOS‐10 equation of state with a constant reference pressure, the algorithm compares nearly exactly to a case discretized onto isopycnal surfaces and using along‐layer diffusion. The algorithm's cost is comparable to that of tracer advection and can be readily implemented into ocean general circulation models.

中文翻译：

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通用坐标，非局部中性扩散算子

我们提出一种中性扩散算子，适用于利用一般垂直坐标的海洋模型。扩散方案在垂直方向使用多项式重建，并在水平局部但垂直在非局部模具中进行示踪通量估计。这些通量是在垂直网格上计算的，该垂直网格是中性密度空间中模型列的超集。使用通量限制器，该算法可局部消散示踪剂极值，并且不会创建新的极值。在理想配置下使用线性状态方程进行的演示表明，该算法是完全中立的。当使用具有恒定参考压力的非线性TEOS-10状态方程时，该算法几乎与离散化到等渗面并使用沿层扩散的情况进行了精确比较。算法'