| | 1 | = PDAFomi_assimilate_lenkf_nondiagR = |
| | 2 | |
| | 3 | This page documents the routine `PDAF_assimilate_lenkf` of PDAF. The routine is used to execute the analysis step of the localized EnKF (LEnKF) with PDAF-OMI for the case of a non-diagonal observation error covariance matrix. This routine was introduced with PDAF V2.3. |
| | 4 | |
| | 5 | The routine is typically called in `assimilate_pdaf` or directly in the model code. |
| | 6 | |
| | 7 | 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 routine [wiki:PDADomi_put_state_lenkf_nondiagR PDAFomi_put_state_lenkf_nondiagR] is used. |
| | 8 | |
| | 9 | Here, we list the full interface of the routine. |
| | 10 | |
| | 11 | The interface when using the LEnKF is the following: |
| | 12 | {{{ |
| | 13 | SUBROUTINE PDAFomi_assimilate_lenkf_nondiagR(U_collect_state, U_distribute_state, & |
| | 14 | U_init_dim_obs_pdafomi, U_obs_op_pdafomi, & |
| | 15 | U_prepoststep, U_localize_covar_pdafomi, & |
| | 16 | U_add_obs_err_pdafomi, U_init_obscovar_pdafomi, & |
| | 17 | U_next_observation, status) |
| | 18 | }}} |
| | 19 | with the following arguments: |
| | 20 | * `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. |
| | 21 | * `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. |
| | 22 | * `U_init_dim_obs_pdafomi`: The name of the user-supplied routine that initializes the observation information and provides the size of observation vector |
| | 23 | * `U_obs_op_pdafomi`: The name of the user-supplied routine that acts as the observation operator on some state vector |
| | 24 | * `U_prepoststep`: The name of the pre/poststep routine as in `PDAF_get_state` |
| | 25 | * `U_localize_covar_pdafomi`: Apply covariance localization to the matrices HP and HPH^T^ |
| | 26 | * `U_add_obs_err_pdafomi`: The name of the user-supplied routine that adds the observation error covariance matrix to the ensemble covariance matrix projected onto the observation space. |
| | 27 | * `U_init_obscovar_pdafomi`: The name of the user-supplied routine that initializes the observation error covariance matrix. |
| | 28 | * `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`. |
| | 29 | * `status`: The integer status flag. It is zero, if `PDAFomi_assimilate_lenkf` is exited without errors. |
| | 30 | |
| | 31 | For the EnKF, the user-supplied routines are essentially executed in the order they are listed in the interface to PDAFomi_assimilate_lenkf_nondiagR. |
| | 32 | |
| | 33 | The user-supplied call-back routines are described on the page on [ImplementAnalysislenkf implementing the analysis step of the local EnKF]. |
| | 34 | |
| | 35 | It is recommended that the value of `status_pdaf` is checked in the program after PDAFomi_assimilate_lenkf_nondiagR is executed. Only if its value is 0 the initialization was successful. |
| | 36 | |
| | 37 | PDAF also has a [PdafSimplifiedInterface Simplified Interface] providing the routine [wiki:PDAFomi_assimilate_lenkf_si PDAFomi_assimilate_lenkf_nondiagR_si]. In the simplified interface, the name of the user-supplied routines have predefined names and do not appear in the call to `PDAFomi_assimilate_lenkf_nondiagR_si`. More information on the pre-defined names is provided in the [ImplementAnalysisLocal page on implementing the analysis step of the local filters]. |
| | 38 | |
