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Data assimilation by delay-coordinate nudging

Abstract: A new nudging method for data assimilation, delay-coordinate nudging, is presented. Delay-coordinate nudging makes explicit use of present and past observations in the formulation of the forcing driving the model evolution at each time step. Numerical experiments with a low-order chaotic system show that the new method systematically outperforms standard nudging in different model and observational scenarios, also when using an unoptimized formulation of the delay-nudging coefficients. A connection between the optimal delay and the dominant Lyapunov exponent of the dynamics is found based on heuristic arguments and is confirmed by the numerical results, providing a guideline for the practical implementation of the algorithm. Delay-coordinate nudging preserves the easiness of implementation, the intuitive functioning and the reduced computational cost of the standard nudging, making it a potential alternative especially in the field of seasonal-to-decadal predictions with large Earth system models that limit the use of more sophisticated data assimilation procedures.

 Fuente: Q. J. R. Meteorol. Soc. 142: 1290?1299, April 2016

 Editorial: Wiley-Blackwell

 Fecha de publicación: 01/04/2016

 Nº de páginas: 10

 Tipo de publicación: Artículo de Revista

 DOI: 10.1002/qj.2732

 ISSN: 0035-9009,1477-870X

 Proyecto español: FIS2014-59462-P

 Url de la publicación: https://doi.org/10.1002/qj.2732