## Abstract

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.

Original language | English (US) |
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Article number | e2019MS001992 |

Journal | Journal of Advances in Modeling Earth Systems |

Volume | 12 |

Issue number | 12 |

DOIs | |

State | Published - Dec 2020 |

## All Science Journal Classification (ASJC) codes

- Global and Planetary Change
- Environmental Chemistry
- General Earth and Planetary Sciences

## Keywords

- diffusion operator
- neutral physics
- ocean model discretization