PDAF_put_state_generate_obs

This page documents the routine PDAF_put_state_generate_obs of PDAF.

The routine is typically called in assimilate_pdaf or directly in the model code.

This routine is used to generate synthetic observations with PDAF. The routines PDAF_put_state_* are used with the 'flexible' implementation variant of PDAF. The general aspects of the filter specific routines PDAF_put_state_* are described on the page Modification of the model code for the ensemble integration and its sub-page on inserting the analysis step. For the 'fully parallel' implementation variant the alternative routine PDAF_generate_obs is used.

The interface is the following:

  SUBROUTINE PDAF_put_state_generate_obs(U_collect_state, U_init_dim_obs_f, U_obs_op_f, U_get_obs_f, &
                                  U_init_obserr_f, U_prepoststep, status_pdaf)

with the following arguments:

• 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 PDAF_get_state.
• U_init_dim_obs_f: The name of the user-supplied routine that provides the size of the full observation vector
• U_obs_op_f: The name of the user-supplied routine that acts as the full observation operator on some state vector
• U_get_obs_f: The name of the user-supplied routine that receives the full vector of generated synthetic observations from PDAF
• 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
• U_prepoststep: The name of the pre/poststep routine as in PDAF_get_state
• status_pdaf: The integer status flag. It is zero, if PDAF_put_state_letkf is exited without errors.

The user-supplied call-back routines are described on the page on implementing the generation of synthetic observations.

It 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.

PDAF also has a Simplified Interface providing the routine PDAF_put_state_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_put_state_generate_obs_si. More information on the pre-defined names is provided in the page on implementing the generation of synthetic observations.