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Spatiotemporal MVL Analysis of EPS: Application to DEMETER multi-model Seasonal Predictions

Conferencia: Exploring Complex Dynamics in High-Dimensional Chaotic Systems: From Weather Forecasting to Oceanic Flows
Año: 2010
Tipo de contribución: Charla invitada
Poster: ECODYC10_Gutierrez.pdf

The main goal of this talk is illustrating the usefulness of some recent spatiotemporal analysis tools in the field of weather prediction. To this aim we first present a recent characterization of spatiotemporal error growth (the so called mean-variance logarithmic (MVL) diagram, Primo et al. 2005, Gutiérrez et al. 2008) and then we describe an application using coupled ocean-atmosphere Ensemble Prediction Systems (Fernández et al. 2009); in particular we consider the DEMETER multimodel seasonal hindcast (http://www.ecmwf.int/research/demeter/) and focus on both initial conditions (three different perturbation procedures) and model errors (seven coupled GCMs). We show that, as opposite to the standard temporal analysis (spatially-averaged or single-point), the MVL spatiotemporal analysis accounts for the nontrivial localization of fluctuations, thus allowing disentangling the effects of the different initialization procedures (random, lagged, singular vectors) and the different model formulations. For instance, it is shown that the shared building blocks of the GCMs (atmospheric and ocean components) impose similar dynamics among different models and, thus, contribute to poorly sampling the model formulation uncertainty.

References:

C. Primo, Rodríguez, M.A. López, J.M. Szendro, I. (2005) Predictability, bred vectors, and generation of ensembles in space-time chaotic systems. Physical Review E, 72, 15201-15206.

J.M. Gutiérrez, C. Primo, M.A. Rodríguez and J. Fernández (2008) Spatiotemporal Characterization of Ensemble Prediction Systems. The Mean-Variance of Logarithms (MVL) Diagram. Nonlinear Processes in Geophysics, 15, 109-114. http://www.nonlin-processes-geophys.net/15/109/2008/npg-15-109-2008.pdf

J. Fernández, C. Primo, A. S. Cofiño, J.M. Gutiérrez, M.A. Rodríguez (2009) MVL Spatiotemporal analysis for model comparison. Application to the DEMETER Multi-model Ensemble. Climate Dynamics, 33, 233-243. DOI: 10.1007/s00382-008-0456-9

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