Changes between Version 11 and Version 12 of ImplementGenerateObs


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Timestamp:
Nov 30, 2020, 1:19:00 PM (7 weeks ago)
Author:
lnerger
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  • ImplementGenerateObs

    v11 v12  
    99Twin data assimilation experiments are a common approach to assess data assimilation methods. In twin experiments one uses the model to generate a ''true'' model state. Further one generates synthetic observations by adding random perturbations to the true state. The, in the actual twin experiment one starts the data assimilation with a state estimate that is different from the true state and assimilates the synthetic observations. One can analyze the assimilation result by comparing the state estimate from the twin experiment with the previously generated true state.
    1010
    11 Starting with version 1.14, PDAF provides functionality to generate synthetic observations. The functionality bases on the normal implementation of the assimilation used with PDAF. However, one can run the observation generation with an ensemble of just one member, which should be initialized with the initial true state. PDAF provides the routines `PDAF_generate_obs` and `PDAF_put_state_generate_obs` to perform the observation generation. These routines use the observation operator routines which the user implements e.g. for assimilating real observations.
     11Starting with version 1.14, PDAF provides functionality to generate synthetic observations. The functionality bases on the normal implementation of the assimilation used with PDAF. However, one can run the observation generation with an ensemble of just one member, which should be initialized with the initial true state. PDAF provides the routines `PDAFomi_generate_obs` and `PDAFomi_put_state_generate_obs` to perform the observation generation. These routines use the observation operator routines which the user implements e.g. for assimilating real observations.
    1212
    1313Here we describes the steps need to generate synthetic obsrvations.
     
    6161Here, all user-supplied routines are described that are required in the call to `PDAF_generate_obs`. For some of the generic routines, we link to the page on [ModifyModelforEnsembleIntegration modifying the model code for the ensemble integration].
    6262
    63 To indicate user-supplied routines we use the prefix `U_`. In the template directory `templates/` as well as in the example implementation in `testsuite/src/dummymodel_1D` these routines exist without the prefix, but with the extension `_pdaf.F90`. In the section titles below we provide the name of the template file in parentheses.
     63To indicate user-supplied routines we use the prefix `U_`. In the template directory `templates/` as well as in the example implementation in `models/lorenz_96/` these routines exist without the prefix, but with the extension `_pdaf.F90`. The two routines `init_dim_obs_pdafomi` and `obs_op_pdafomi` are part of PDAF-OMI and are contained in the file `callback_obs_pdafomi.F90`. In the section titles below we provide the name of the template file in parentheses.
    6464
    6565In the subroutine interfaces some variables appear with the suffix `_p` (short for 'process'). This suffix indicates that the variable is particular to a model sub-domain, if a domain decomposed model is used. Thus, the value(s) in the variable will be different for different model sub-domains. In addition, there will be variables with the suffix `_f` (for 'full').