wiki:PDAFomi_assimilate_local

Version 1 (modified by lnerger, 12 months ago) (diff)

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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 Kalman filters (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 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.