PDAF-OMI Observation Diagnostics

The PDAF-OMI observation diagnostics module provides functionality to obtain statistics about the differences between observations and the observed model state. In addition, there are routines that provide the user access to the observations and observed quantities like the observed ensemble mean state.

Here, we describe the functionalities of the observation diagnostics routines.

A common place to call the PDAFomi_diag diagnostics routines is in prepoststep_pdaf, which is the usual place to also analyze the ensemble. Usually, PDAF initializes the observations after prepoststep_pdaf was executed after the forecast. To be able to compare the observations and the forecast ensemble, one has to switch the place at which observations are initialized. This is done with

  CALL PDAF_set_iparam(9, 0)

which can be called in init_pdaf after the initialization of PDAF with PDAF_init.

The routines for observation diagnostics can be organized in four groups

• Activation of observation diagnostics
  • [PDAFomi_observation_diagnostics#PDAFomi_set_obs_diag PDAFomi_set_obs_diag]
• Statistics
  • PDAFomi_diag_rmsd
  • PDAFomi_diag_stats
• Access to observation dimensions
  • PDAFomi_diag_nobs
  • PDAFomi_diag_dimobs
• Acces to observation arrays
  • PDAFomi_diag_get_obs
  • PDAFomi_diag_get_HXmean
  • PDAFomi_diag_get_HX
  • PDAFomi_diag_get_ivar

Activation of observation diagnostics

PDAFomi_set_obs_diag

The routine is used to activate or deactivate the observation diagnostics.

The routine can be called by all processes, but it is sufficient to call it for those processes that handle observations, which usually are the filter processes. A common place is to call the routine in init_pdaf afer the initialization of PDAF in PDAF_init.

The interface is:

  SUBROUTINE PDAFomi_set_obs_diag(diag)

    INTEGER, INTENT(in) :: diag   ! Value for observation diagnostics mode
                                  ! >0 activates observation diagnostics