Changes between Initial Version and Version 1 of PDAF_generate_obs


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Timestamp:
Feb 9, 2019, 11:21:17 AM (5 years ago)
Author:
lnerger
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  • PDAF_generate_obs

    v1 v1  
     1= PDAF_generate_obs =
     2
     3This page documents the routine `PDAF_generate_obs` of PDAF.
     4
     5The routine is typically called in `assimilate_pdaf` or directly in the model code.
     6
     7This routine is used to generate synthetic observations. It bases on the usual implementation strategy for PDAF which is described on the page [ModifyModelforEnsembleIntegration Modification of the model code for the ensemble integration] and its sub-page on [InsertAnalysisStep inserting the analysis step]. The routine is used in the fully-parallel implementation variant of the data assimilation system. When the 'flexible' implementation variant, the routine `PDAF_put_state_generate_obs' is used.
     8
     9
     10
     11The interface is the following:
     12{{{
     13  SUBROUTINE PDAF_generate_obs(U_collect_state, U_distribute_state, &
     14                                  U_init_dim_obs_f, U_obs_op_f, U_get_obs_f, U_init_obserr_f, &
     15                                  U_prepoststep, U_next_observation, status_pdaf)
     16}}}
     17with the following arguments:
     18 * `U_collect_state`: The name of the user-supplied routine that initializes a state vector from the array holding the ensemble of model states from the model fields. This is basically the inverse operation to `U_distribute_state` used in [ModifyModelforEnsembleIntegration#PDAF_get_state PDAF_get_state]
     19 * `U_distribute_state`:  The name of a user supplied routine that initializes the model fields from the array holding the ensemble of model state vectors.
     20 * `U_init_dim_obs_f`: The name of the user-supplied routine that provides the size of the full observation vector
     21 * `U_obs_op_f`: The name of the user-supplied routine that acts as the full observation operator on some state vector
     22 * `U_get_obs_f`: The name of the user-supplied routine that receives the full vector of generated synthetic observations from PDAF
     23 * `U_init_obserr_f`: The name of the user-supplied routine that initializes the vector of observations error standard deviations for for full observation vector
     24 * `U_prepoststep`: The name of the pre/poststep routine as in `PDAF_get_state`
     25 * `U_next_observation`: The name of a user supplied routine that initializes the variables `nsteps`, `timenow`, and `doexit`. The same routine is also used in `PDAF_get_state`.
     26 * `status_pdaf`: The integer status flag. It is zero, if `PDAF_assimilate_lestkf` is exited without errors.
     27
     28It is recommended that the value of `status_pdaf` is checked in the program after PDAF_generate_obs is executed. Only if its value is 0 the initialization was successful.
     29
     30PDAF also has a [PdafSimplifiedInterface Simplified Interface] providing the routine `PDAF_generate_obs_si`. In the simplified interface, the name of the user-supplied routines have predefined names and do not appear in the call to `PDAF_generate_obs_si`.