Stochastic representation of mesoscale eddy effects in coarse-resolution barotropic models

Werner Bauer (1) , Pranav Chandramouli (1) , Long Li (2, 3) , Etienne Mémin (1)

1 FLUMINANCE - Fluid Flow Analysis, Description and Control from Image Sequences
2 IRMAR - Institut de Recherche Mathématique de Rennes
3 Inria Rennes – Bretagne Atlantique

A stochastic representation based on a physical transport principle is proposed to account for mesoscale eddy effects on the evolution of the large-scale flow. This framework arises from a decomposition of the Lagrangian velocity into a smooth in time component and a highly oscillating term. One important characteristic of this random model is that it conserves the energy of any transported scalar. Such an energy-preserving representation is tested for the coarse simulation of a barotropic circulation in a shallow ocean basin, driven by a symmetric double-gyres wind forcing. The empirical spatial correlation of the random small-scale velocity is estimated from data of an eddy-resolving simulation. After reaching a turbulent equilibrium state, a statistical analysis of tracers shows that the proposed random model enables us to reproduce accurately, on a coarse mesh, the local structures of the first four statistical moments (mean, variance, skewness and kurtosis) of the high-resolution eddy-resolved data.

Mots clés: Wind-driven circulation; Stochastic modelling; Mesoscale eddies; Geostrophic turbulence

Domaines: Océan, Atmosphère; Dynamique des Fluides [physics.flu-dyn]; Systèmes dynamiques [math.DS]; Physique mathématique [math-ph]; Statistiques [math.ST]

Werner Bauer, Pranav Chandramouli, Long Li, Etienne Mémin. Stochastic representation of mesoscale eddy effects in coarse-resolution barotropic models. Ocean Modelling, 2020, 151, pp.1-50. ⟨10.1016/j.ocemod.2020.101646⟩. ⟨hal-02666147⟩