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Link between stochastic grid perturbation and location uncertainty framework
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  • Simon Clement,
  • Eric Blayo,
  • Laurent Debreu,
  • Jean-Michel Brankart,
  • Pierre Brasseur,
  • Long Li,
  • Etienne Mémin
Simon Clement
Univ. Grenoble Alpes
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Eric Blayo
Univ. Grenoble Alpes

Corresponding Author:[email protected]

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Laurent Debreu
Inria, Frenoble, France
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Jean-Michel Brankart
CNRS
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Pierre Brasseur
French National Centre for Scientific Research (CNRS)
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Long Li
Centre Inria Rennes - Bretagne Atlantique
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Etienne Mémin
Inria
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Abstract

This paper investigates the relationship between a Stochastic Grid Perturbation (SGP) and Location Uncertainty (LU). The LU formulation, which introduces random velocity fluctuations, has shown efficacy in organizing large-scale flow and replicating long-term statistical characteristics. SGP was created as a simpler approach which perturbs the computational grid for ensemble members, aiming to simulate small uncertainties in high-resolution predictability studies. We aim to clarify the link between SGP and LU. After introducing the LU formalism, we derive the SGP method and discuss its connection to LU. Correlated noise in time is introduced in the SGP method to preserve the structure of the original grid. A compensating advection term is shown to preserve LU properties despite the latter correlated noise. Numerical experiments on a 3-layer Quasi-Geostrophic model compare various SGP implementations with an explicit LU implementation, highlighting the importance of the compensating advection term to achieve strict equivalence.
17 Jul 2024Submitted to ESS Open Archive
17 Jul 2024Published in ESS Open Archive