PDAF3_assim_offline_local

This page documents the routine PDAF3_assim_offline_local of PDAF. The routine is part of the advanced PDAF3 interface that was introduced with PDAF V3.0.

The routine is universal and can be used to execute the analysis step of all, local and global, ensemble filters. The routine uses the functionalities provided by PDAF-OMI to yield a small number of arguments. This routine exists for simplified transition of implementations for PDAF2. For this, the routine does not use PDAFlocal, but lets the user provide the routines for filling the local state vector and to fill the global analysis state vectors with the local analysis states. This allows to easily transfer from using PDAFomi_put_state_local of PDAF 2. Generally, we recommend to use the routine PDAF3_assim_offline that uses also PDAFlocal.

The routine is used for the offline coupled mode of PDAF, which is described on the page: Implementation Guide for Offline Coupling.

The interface for the routine PDAF3_put_state_local contains names for routines that operate on the local analysis domains (marked by the suffix _l).

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

  SUBROUTINE PDAF3_assim_offline_local(U_init_dim_obs_pdafomi, U_obs_op_pdafomi, &
             U_init_n_domains, U_init_dim_l, U_init_dim_obs_l_pdafomi, &
             U_g2l_state, U_l2g_state, &
             U_prepoststep, status)

with the following arguments:

• U_init_dim_obs_pdafomi:
  The name of the user-supplied routine that initializes the observation information and provides the size of observation vector. This routine is part of an OMI observation module.
• U_obs_op_pdafomi:
  The name of the user-supplied routine that acts as the observation operator on some state vector. This routine is part of an OMI observation module.
• U_init_n_domains:
  The name of the user-supplied routine that provides the number of local analysis domains
• U_init_dim_l:
  The name of the user-supplied routine that provides the state dimension for a local analysis domain
• U_init_dim_obs_l_pdafomi:
  The name of the user-supplied routine that initializes the size of the observation vector for a local analysis domain. This routine is part of an OMI observation module.
• 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_prepoststep:
  The name of the user-supplied pre/poststep routine as in PDAF_get_state
• status:
  The integer status flag. It is zero, if the routine is exited without errors.

Notes:

• The routine is identical to the routine PDAFlocalomi_put_state of PDAF 2.3, except that the argument U_prepostep is at a different place here. Further U_collect_state is not present.
• 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.
• To use the localization in the ENSRF/EAKF, one needs to call PDAFomi_set_localize_covar in the observation modules to initialize the localization information.
• If one only uses the global filters or the LEnKF and ENSRF/EAKF, the routines U_init_n_domains, U_init_dim_l, U_init_dim_obs_l_pdafomi, U_g2l_state, U_l2g_state only need to be present. Because they are never called for global filters, they do not need to be completed with functionality. For example, one can just use the template files for these routines.
• If one only uses the global filters and the LEnKF one can also use alternative routine PDAF3_assim_offline_global, in which the routines for localization are not in the interface.
• It is recommended to check the value of status_pdaf in the program after the routine is executed. Only if its value is 0 the initialization was successful.

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