= PDAFomi_put_state_generate_obs = This page documents the routine `PDAFomi_put_state_generate_obs` of PDAF. It is used with PDAF-OMI 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 `PDAFomi_put_state_*` are used with the 'flexible' implementation variant of PDAF. The general aspects of the filter specific routines `PDAFomi_put_state_*` are described on the page [ModifyModelforEnsembleIntegration Modification of the model code for the ensemble integration] and its sub-page on [InsertAnalysisStep inserting the analysis step]. For the 'fully parallel' implementation variant the alternative routine `PDAFomi_generate_obs` is used. The interface is the following: {{{ SUBROUTINE PDAFomi_put_state_generate_obs(U_collect_state, U_init_dim_obs_pdafomi, U_obs_op_pdafomi, U_get_obs_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 [ModifyModelforEnsembleIntegration#PDAF_get_state PDAF_get_state]. * `U_init_dim_obs_pdafomi`: The name of the user-supplied routine that initializes the observation information and provides the size of observation vector * `U_obs_op_pdafomi`: The name of the user-supplied routine that acts as the 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_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_generate_obs` is exited without errors. The user-supplied call-back routines are described on the [ImplementGenerateObs page on implementing the generation of synthetic observations]. It is recommended that the value of `status_pdaf` is checked in the program after PDAFomi_generate_obs is executed. Only if its value is 0 the initialization was successful. PDAF also has a [PdafSimplifiedInterface Simplified Interface] providing the routine `PDAFomi_put_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 `PDAFomi_put_state_generate_obs_si`.