= PDAF_iau_init_inc = 

This page documents the routine `PDAF_iau_init_inc` of PDAF, which was introduced with PDAF V3.0.

This routine can be used by a user to fill the process-local increment array.
A common use is when the IAU should be applied from the initial time of a run, for example if the increment was computed in a previous assimilation run and then stored for restarting. Since PDAF can only compute an increment in an analysis step, the user needs to provide the increment.

The routine is usually called in `init_pdaf` after the initialization of IAU with `PDAF_iau_init`. It has to be called by all processes that are model processes and one needs to provide the task-local ensemble (i.e. with local ensemble size `dim_ens_l=1` for the fully parallel mode, and usually `dim_ens_l>1` for the flexible parallelization mode). The routine can usually not be called in `init_ens_pdaf` since this routine is only executed by filter processes and not all model processes.

The interface is the following:
{{{
  SUBROUTINE PDAF_iau_init_inc(dim_p, dim_ens_l, ens_inc, flag)

    INTEGER, INTENT(in) :: dim_p                    ! PE-local dimension of model state
    INTEGER, INTENT(in) :: dim_ens_l                ! Task-local size of ensemble
    REAL, INTENT(in) :: ens_inc(dim_p, dim_ens_l)   ! PE-local increment ensemble
    INTEGER, INTENT(out) :: flag                    ! Status flag
}}}