PDAFomi_diag_get_ivar

This page documents the routine PDAFomi_diag_get_ivar of PDAF, which was introduced with PDAF V3.0. This is part of the PDAF-OMI observation diagnostics module.

The routine returns a pointer to a vector of the inverse observation error variances for the specified observation type (id_obs).

Usually all PDAFomi_diag routines are called in prepoststep_pdaf where the observation information can be retrieved and analyzed.

The interface is:

  SUBROUTINE PDAFomi_diag_get_ivar(id_obs, dim_obs_p_diag, ivar_p_ptr)

    INTEGER, INTENT(in)  :: id_obs                   ! Index of observation type to return
    INTEGER, INTENT(out) :: dim_obs_p_diag           ! Observation dimension
    REAL, POINTER, INTENT(out) :: ivar_p_ptr(:)      ! Pointer to inverse observation error variances

Notes:

• In case of a parallelized model, the vector ivar_p_prt contains the observed ensemble mean for the process-sub-domain
• In Fortran user code the pointer to the vector of inverse observation variances should be declared in the form
  REAL, POINTER :: ivar_p_ptr(:)
  It does not need to be allocated. The target vector has the length dim_obs_p_diag.
• If the observation diagnostics have not be activated by using PDAFomi_set_obs_diag the pointer will not be set and dim_obs_diag=0 will be returned. This value can be checked before assessing the pointer array.
• If the feature thisobs%inno_omit is used (see the page Additional functionality of PDAF-OMI), the inverse variance of the omitted observations will show the small value set by inno_omit. One can use this information to exclude such observations when analyzing differences between observations and observed ensemble.