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Finite-volume discretization of the quasi-geostrophic equations with implicit dissipation
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  • Louis Thiry,
  • Long Li,
  • Guillaume Roullet,
  • Etienne Mémin
Louis Thiry
Centre Inria Rennes - Bretagne Atlantique

Corresponding Author:[email protected]

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Long Li
Centre Inria Rennes - Bretagne Atlantique
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Guillaume Roullet
Univ. Brest, CNRS, IRD, Ifremer, Laboratoire d'Oc\'eanographie Physique et Spatiale (LOPS), IUEM, Brest, France
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Etienne Mémin
Inria
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Abstract

We present in this work a new discretization of the multi-layer quasi-geostrophic (QG) model that relies on implicit dissipation rather than additional explicit dissipation.
It is first based on the staggered discretization of the potential vorticity (PV) and the stream-function in order to solve the PV advection with a finite volume method.
This ensures the exact material conservation of the PV.
We compute PV fluxes with a WENO-5 interpolation whose implicit dissipation replaces the usual explicit (hyper-)viscous dissipation.
We propose a new method for solving reversibly the elliptic equation which is nontrivial with this staggered discretization.
The presented discretization does not require the tuning of any additional parameter, \textit{e.g.} additional hyper-viscosity.
We test the proposed method on a challenging idealized wind-driven double-gyre configuration at eddy-resolving, eddy-permitting, and non-eddy-resolving resolutions.
In the eddy-permitting and non-eddy-resolving resolutions, our method produces an eastward jet contrary to usual discretizations without parametrization.
Moreover, our method produces statistics that have a stronger coherence across resolutions than usual discretizations.
We release a very short, concise, and efficient PyTorch implementation of our method to facilitate future data assimilation or machine-learning developments upon this new discretization.
06 Jan 2023Submitted to ESS Open Archive
17 Jan 2023Published in ESS Open Archive