Time‐space weak‐constraint data assimilation for nonlinear models |
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| Authors: | FRANCESCO UBOLDI MASAFUMI KAMACHI |
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| Institution: | Magritte s.n.c., corso San Gottardo 41, 20136 Milano MI, Italy;;Ocean Research Department, Meteorological Research Institute, 1‐1 Nagamine, Tsukuba, Ibaraki 305‐0052 Japan |
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| Abstract: | A general perturbation–linearization scheme is proposed for the problem of data assimilation with an imperfect and nonlinear model, allowing for the application of the weak constraint representer method. The scheme is shown in discrete formalism for a generic model. An application example is given with computer‐generated data in the case of the Burgers equation. Discussion in reference to the assimilation example concerns: the rôle of the model error, seen as a forcing term in the dynamics; the rôle of representers as a posteriori error covariances; a comparison among different choices for a priori dynamic error variance and strong constraint assimilation. Weak and strong constraint methods are also compared in a forecasting experiment. |
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