= PDAFlocalomi_assimilate_en3dvar_lestkf = 

This page documents the routine `PDAFlocalomi_assimilate_en3dvar_lestkf` of PDAF. 

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

The general aspects of the filter specific routines `PDAFomi_assimilate_*` 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]. The routine is used in the fully-parallel implementation variant of the data assimilation system. When the 'flexible' implementation variant, the routines `PDAF_put_state_*' are used. 


The interface is:
{{{
SUBROUTINE PDAFlocalomi_assimilate_en3dvar_lestkf(U_collect_state, U_distribute_state, &
                                 U_init_dim_obs_pdafomi, U_obs_op_pdafomi, &
                                 U_cvt_ens, U_cvt_adj_ens, U_obs_op_lin_pdafomi, &  
                                 U_obs_op_adj_pdafomi, &
                                 U_init_n_domains_p, U_init_dim_l, U_init_dim_obs_l_pdafomi, &
                                 U_prepoststep, U_next_observation, outflag)
}}}
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` as well as here. 
 * `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.
 * `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_cvt_ens`: The name of the user-supplied routine that applies the ensemble control-vector transformation (square-root of the B-matrix) on some control vector to obtain a state vector.
 * `U_cvt_adj_ens]: The name of the user-supplied routine that applies the adjoint ensemble control-vector transformation (with square-root of the B-matrix) on some state vector to obtain the control vector.
 * `U_obs_op_lin_pdafomi`: The name of the user-supplied routine that acts as the linearized observation operator on some state vector
 * `U_obs_op_adj_pdafomi`: The name of the user-supplied routine that acts as the adjoint observation operator on some state vector
 * `U_init_n_domains`: The name of the routine that provides the number of local analysis domains
 * `U_init_dim_l`: The name of the routine that provides the state dimension for a local analysis domain
 * `U_init_dim_obs_l_pdafomi`: The name of the routine that initializes the size of the observation vector for a local analysis domain
 * `U_prepoststep`: The name of the pre/poststep routine as in `PDAF_get_state`
 * `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`.
 * `status`: The integer status flag. It is zero, if the routine is exited without errors.


The user-supplied call-back routines are described on the page on [wiki:ImplementAnalysis_3DEnVar implementing the analysis step of 3D Ensemble Var with OMI].

It is recommended that the value of `status_pdaf` is checked in the program after the routine is executed. Only if its value is 0 the initialization was successful.