| | 1 | = PDAF_assimilate_letkf = |
| | 2 | |
| | 3 | This page documents the routine `PDAF_assimilate_letkf` of PDAF. |
| | 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 `PDAF_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. |
| | 8 | |
| | 9 | The interface when using the LETKF algorithm is the following: |
| | 10 | {{{ |
| | 11 | SUBROUTINE PDAF_assimilate_letkf(U_collect_state, U_distribute_state, U_init_dim_obs_f, U_obs_op_f, & |
| | 12 | U_init_obs_f, U_init_obs_l, U_prepoststep, U_prodRinvA_l, & |
| | 13 | U_init_n_domains, U_init_dim_l, U_init_dim_obs_l, & |
| | 14 | U_g2l_state, U_l2g_state, U_g2l_obs, & |
| | 15 | U_init_obsvar, U_init_obsvar_l, U_next_observation, status_pdaf) |
| | 16 | }}} |
| | 17 | with 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_init_obs_f`: The name of the user-supplied routine that initializes the full vector of observations |
| | 23 | * `U_init_obs_l`: The name of the user-supplied routine that initializes the vector of observations for a local analysis domain |
| | 24 | * `U_prepoststep`: The name of the pre/poststep routine as in `PDAF_get_state` |
| | 25 | * `U_prodRinvA_l`: The name of the user-supplied routine that computes the product of the inverse of the observation error covariance matrix with some matrix provided to the routine by PDAF. |
| | 26 | * `U_init_n_domains`: The name of the routine that provides the number of local analysis domains |
| | 27 | * `U_init_dim_l`: The name of the routine that provides the state dimension for a local analysis domain |
| | 28 | * `U_init_dim_obs_l`: The name of the routine that initializes the size of the observation vector for a local analysis domain |
| | 29 | * `U_g2l_state`: The name of the routine that initializes a local state vector from the global state vector |
| | 30 | * `U_l2g_state`: The name of the routine that initializes the corresponding part of the global state vector from the the provided local state vector |
| | 31 | * `U_g2l_obs`: The name of the routine that initializes a local observation vector from a full observation vector |
| | 32 | * `U_init_obsvar`: The name of the user-supplied routine that provides a global mean observation error variance (This routine will only be executed, if an adaptive forgetting factor is used) |
| | 33 | * `U_init_obsvar_l`: The name of the user-supplied routine that provides a mean observation error variance for the local analysis domain (This routine will only be executed, if a local adaptive forgetting factor is used) |
| | 34 | * `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`. |
| | 35 | * `status_pdaf`: The integer status flag. It is zero, if `PDAF_assimilate_letkf` is exited without errors. |
| | 36 | |
| | 37 | |
| | 38 | |
| | 39 | Note: |
| | 40 | * The order of the routine names does not show the order in which these routines are executed. See the [ImplementAnalysisletkf#Executionorderofuser-suppliedroutines section on the order of the execution] in the page on implementing the analysis step of the LETKF algorithm. |
| | 41 | |
| | 42 | The user-supplied call-back routines are described on the page on [ImplementAnalysisletkf implementing the analysis step of the LETKF]. |
| | 43 | |
| | 44 | It is recommended that the value of `status_pdaf` is checked in the program after PDAF_assimilate_letkf is executed. Only if its value is 0 the initialization was successful. |
| | 45 | |
| | 46 | PDAF also has a [PdafSimplifiedInterface Simplified Interface] providing the routine `PDAF_assimilate_letkf_si`. In the simplified interface, the name of the user-supplied routines have predefined names and do not appear in the call to `PDAF_assimilate_letkf_si`. More information on the pre-defined names is provided in the [ImplementAnalysisletkf page on implementing the analysis step of the LETKF algorithm]. |
