Data assimilation by delay-coordinate nudging

Pazó, D., Carrassi, A. ORCID: https://orcid.org/0000-0003-0722-5600 and López, J. M. (2016) Data assimilation by delay-coordinate nudging. Quarterly Journal of the Royal Meteorological Society, 142 (696). pp. 1290-1299. ISSN 0035-9009 doi: 10.1002/qj.2732

Abstract/Summary

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.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/90279
Item Type	Article
Refereed	Yes
Divisions	No Reading authors. Back catalogue items Science > School of Mathematical, Physical and Computational Sciences > National Centre for Earth Observation (NCEO) Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
Publisher	Wiley
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