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Geophysical flows under location uncertainty, Part II Quasi-geostrophy and efficient ensemble spreading
Abstract : Models under location uncertainty are derived assuming that a component of the velocity is uncorrelated in time. The material derivative is accordingly modified to include an advection correction, inhomogeneous and anisotropic diffusion terms and a multiplicative noise contribution. In this paper, simplified geophysical dynamics are derived from a Boussinesq model under location uncertainty. Invoking usual scaling approximations and a moderate influence of the subgrid terms, stochastic formulations are obtained for the stratified Quasi-Geostrophy (QG) and the Surface Quasi-Geostrophy (SQG) models. Based on numerical simulations, benefits of the proposed stochastic formalism are demonstrated. A single realization of models under location uncertainty can restore small-scale structures. An ensemble of realizations further helps to assess model error prediction and outperforms perturbed deterministic models by one order of magnitude. Such a high uncertainty quantification skill is of primary interests for assimilation ensemble methods. MATLAB R code examples are available online.
https://hal.inria.fr/hal-01391476
Contributor : Valentin Resseguier <>
Submitted on : Friday, March 10, 2017 - 6:47:01 AM
Last modification on : Wednesday, March 31, 2021 - 3:36:34 AM
Long-term archiving on: : Sunday, June 11, 2017 - 12:33:36 PM
Contributor : Valentin Resseguier <>
Submitted on : Friday, March 10, 2017 - 6:47:01 AM
Last modification on : Wednesday, March 31, 2021 - 3:36:34 AM
Long-term archiving on: : Sunday, June 11, 2017 - 12:33:36 PM
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