4D Variational Data Assimilation for Locally Nested Models : complementary theoretical aspects and application to a 2D shallow water model - Inria - Institut national de recherche en sciences et technologies du numérique Access content directly
Journal Articles International Journal for Numerical Methods in Fluids Year : 2011

4D Variational Data Assimilation for Locally Nested Models : complementary theoretical aspects and application to a 2D shallow water model

Abstract

We consider the application of a four-dimensional variational data assimilation method to a numerical model, which employs local mesh refinement to improve its solution. We focus on structured meshes where a high-resolution grid is embedded in a coarser resolution one, which covers the entire domain. The formulation of the nested variational data assimilation algorithm was derived in a preliminary work (Int. J. Numer. Meth. Fluids 2008). We are interested here in complementary theoretical aspects. We present first a model for the multi-grid background error covariance matrix. Then, we propose a variant of our algorithms based on the addition of control variables in the inter-grid transfers in order to allow for a reduction of the errors linked to the interactions between the grids. These formulations are illustrated and discussed in the test case experiment of a 2D shallow water model.

Dates and versions

hal-00658105 , version 1 (09-01-2012)

Identifiers

Cite

Ehouarn Simon, Laurent Debreu, Eric Blayo. 4D Variational Data Assimilation for Locally Nested Models : complementary theoretical aspects and application to a 2D shallow water model. International Journal for Numerical Methods in Fluids, 2011, 66 (2), pp.135-161. ⟨10.1002/fld.2244⟩. ⟨hal-00658105⟩
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