PDAFomi_assimilate_local

This page documents the routine PDAF_assimilate_local of PDAF. The routine is used to execute the analysis step of all local ensemble filters including the nonlinear filter LNETF (but except the LEnKF) with PDAF-OMI.

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 Modification of the model code for the ensemble integration and its sub-page on 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 PDAomi_put_state_local? is used.

The interface for the routine PDAFomi_assimilate_local contains names for routines that operate on the local analysis domains (marked by the suffix _l). Further there are routines that convert between a local and a global model state vector (U_g2l_state and U_l2g_state). Here, we list the full interface of the routine. Subsequently, the user-supplied routines specified in the call is explained.

The interface when using one of the local filters is the following:

  SUBROUTINE PDAFomi_assimilate_local(U_collect_state, U_distribute_state, &
                                  U_init_dim_obs_pdafomi, U_obs_op_pdafomi, &
                                  U_prepoststep, U_init_n_domains, U_init_dim_l, &
                                  U_init_dim_obs_l_pdafomi, U_g2l_state, U_l2g_state, &
                                  U_next_observation, status)

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 and also 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_prepoststep: The name of the pre/poststep routine as in PDAF_get_state
• 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_g2l_state: The name of the routine that initializes a local state vector from the global state vector
• U_l2g_state: The name of the routine that initializes the corresponding part of the global state vector from the provided local state vector
• 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 PDAFomi_assimilate_local is exited without errors.

Note:

• The order of the routine names does not show the order in which these routines are executed. See the section on the order of the execution on the page on implementing the analysis step of the local filter algorithms.

The user-supplied call-back routines are described on the page on implementing the analysis step of the local filters.

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

PDAF also has a Simplified Interface providing the routine PDAFomi_assimilate_local_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_local_si. More information on the pre-defined names is provided in the page on implementing the analysis step of the local filters.