PDAF_assim_offline_enkf

This page documents the routine PDAF_assim_offline_enkf of PDAF. The routine was introduced with PDAF V3.0.

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

The interface when using the EnKF is the following:

  SUBROUTINE PDAF_assim_offline_enkf(U_init_dim_obs, U_obs_op, &
                                 U_init_obs, U_prepoststep, U_add_obs_err, U_init_obscovar, status_pdaf)

with the following arguments:

• U_init_dim_obs: The name of the user-supplied routine that provides the size of observation vector
• U_obs_op: The name of the user-supplied routine that acts as the observation operator on some state vector
• U_init_obs: The name of the user-supplied routine that initializes the vector of observations
• U_prepoststep: The name of the pre/poststep routine as in PDAF_get_state
• U_add_obs_err: The name of the user-supplied routine that adds the observation error covariance matrix to the ensemble covariance matrix projected onto the observation space.
• U_init_obscovar: The name of the user-supplied routine that initializes the observation error covariance matrix.
• status_pdaf: The integer status flag. It is zero, if the routine is exited without errors.

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

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