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Original Research Papers

Determination of optimal nudging coefficients

Authors:

P. A. Vidard ,

Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique, 42, avenue Coriolis, 31057 Toulouse, FR
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F.-X. Le Dimet,

Laboratoire de Modélisation et Calcul., Université Joseph Fourier, BP 53 38041 Grenoble, FR
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A. Piacentini

Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique, 42, avenue Coriolis, 31057 Toulouse, FR
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Abstract

A four-dimensional variational assimilation (4D-Var) scheme is now widely used by meteorological centres in a operational way. However, most of these applications do not take account of model error. Indeed, the classical 4D-Var with imperfect model formulation is unaffordable for current computational means. This paper presents a low-cost method for dealing with model errors in 4D variational assimilation. This method can be formally compared to a Kalman filter. This new scheme is tested on two configurations: first on a Burger equation, which allows one to calibrate the method, and second on a more relevant shallow-water equations model, both in a twin experiment framework. It is shown that, compared to classical 4D-Var results, this method provides a noticeable improvement.

How to Cite: Vidard, P.A., Le Dimet, F.-X. and Piacentini, A., 2003. Determination of optimal nudging coefficients. Tellus A: Dynamic Meteorology and Oceanography, 55(1), pp.1–15. DOI: http://doi.org/10.3402/tellusa.v55i1.14576
  Published on 01 Jan 2003
 Accepted on 31 Jul 2002            Submitted on 28 May 2001

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