Changes between Version 10 and Version 11 of OfflineImplementationGuide


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Timestamp:
Dec 21, 2016, 1:23:28 PM (4 years ago)
Author:
lnerger
Comment:

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  • OfflineImplementationGuide

    v10 v11  
    3535
    3636An overview of the available options for each filter that can be specified when PDAF is initialized is given on the [wiki:AvailableOptionsforInitPDAF overview page on options].
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     39== Generating initial ensembles ==
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     41To perform ensemble data assimilation one has to create an initial ensemble which is then used in the data assimilation process. There are various different ways to generate an ensemble (like random picking of model states, breeding, short-term integrations of perturbed model fields, second-order exact sampling from EOFs). PDAF provides routines to use snapshots from a model integration to first compute EOFs (empirical orthogonal functions) and then to use the EOFs to perform a constrained random transformation to obtain ensemble perturbations to which a central state (i.e. ensemble mean) is added. This second-order exact sampling (Pham, 2001) showed good performance in our own data assimilation applications.
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     43The ensemble generation is described on the separate page:
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     45 1. [EnsembleGeneration Ensemble Generation]