Changes between Version 6 and Version 7 of OMI_observation_modules_PDAF3

Timestamp:

Jun 4, 2025, 2:43:58 PM (44 hours ago)

Author:

lnerger

Comment:

--

OMI_observation_modules_PDAF3

@@ -87 +87 @@
 == `init_dim_obs_OBSTYPE` ==
 
-This is the main routine to initialize observation information. 
+This is the main routine to initialize observation information. In addition, this routine is used to initialize information for covariance localization in the LEnKF, EnSRF and EAKF methods.
 
 ||= Please see the template file `templates/omi/obs_OBSTYPE_pdafomi_TEMPLATE.F90`[[br]] for a step-by-step description of the implementation steps. =||
@@ -123 +123 @@
  * `cradius` is always a single value. It should be set of the largest radius of the directions in which the process domain is split by parallelization. It defines the radius within which observations from neighboring process domains are taken into account.
 
+=== Initializing covariance localization ===
+
+The covariance localization should be initialized in `init_dim_obs_OBSTYPE`. This is achieved by calling `PDAFomi_set_localize_covar`. The routine can only be called after the call to `PDAFomi_gather_obs`.
+
+The interface is for isotropic localization:
+{{{
+  SUBROUTINE PDAFomi_set_localize_covar(thisobs, dim_p, ncoords, coords, &
+       locweight, cradius, sradius)
+
+    TYPE(obs_f), INTENT(inout) :: thisobs           ! Data type with full observation
+    INTEGER, INTENT(in) :: dim_p                    ! State dimension
+    INTEGER, INTENT(in) :: ncoords                  ! Number of coordinate directions
+    REAL, INTENT(in)    :: coords_p(dim_p,ncoords)  ! Coordinates of state vector elements
+    INTEGER, INTENT(in) :: locweight                ! Localization weight type
+    REAL, INTENT(in)    :: cradius                  ! localization radius
+    REAL, INTENT(in)    :: sradius                  ! Support radius for weight functions
+}}}
+
+'''Notes:'''
+ * The routine allows to specify the localization radius and support radius (`lradius`, `sradius`) and localization function (`locweight`) individually for each observation type. 
+ * The coordinate array `coords_p` specifies the coordinates of each element in the state vector for the process local sub-domain. The coordinate units have to be consistent with those used to specify the coordinates of observations.
+ * The routine only supports a fixed localization radius throughout the domain.
+ * One can also directly call the routine `PDAFomi_set_localize_covar_iso`, e.g. when calling from a program coded in C. 
+
+There is also a variant of this routine for non-isotropic localization. See the [wiki:PDAFomi_set_localize_covar Documentation on PDAFomi_set_localize_covar] for more information.
 
 == `obs_op_OBSTYPE` ==
@@ -175 +200 @@
 
 == `localize_covar_OBSTYPE` ==
+
+|| This routine exists for backward compatibility. In PDAF V3.0, we added the routine [wiki:OMI_observation_modules_PDAF3#Initializingcovariancelocalization PDAFomi_set_localize_covar], which was decribed above. When PDAFomi_set_localize_covar is used, the user-provided routine `localize_covar_OBSTYPE` is no longer required. ||
 
 This routine initializes local observation information. The routine is only used by the local EnKF (LEnKF).