Changes between Version 4 and Version 5 of OMI_additional_functionality_PDAF3

Timestamp:

Apr 17, 2026, 12:11:18 PM (13 hours ago)

Author:

lnerger

Comment:

--

OMI_additional_functionality_PDAF3

@@ -167 +167 @@
 This function only supports geographic coordinates given in radians.
 
+== Optimizing the local observation search ==
+
+With PDAF V3.1 we revised the search for local observations in `PDAFomi_init_dim_obs_l` to improve its performance. this is used in the domain-localized DA methods (LESTKF, LETKF, LNETF, LKNETF, LSEIK).
+
+The performance of the search operation is case specific and depends, e.g., on the available observations, the localiztion radius, kind of coordinates (Cartesian or geograpic) and on whether an isotropic and non-isotropic localization is used. While the default choice of the search operation usually gives a good performance, one can try to optimize the speed of the search by more sophisticated variants. For this, one can select the type of the search operation by calling `PDAFomi_set_searchtype`.
+
+=== PDAFomi_set_searchtype ===
+
+This routine selects the type of the search operation for local observations.
+
+The interface is:
+{{{
+  SUBROUTINE PDAFomi_set_searchtype(search_type, sortdir)
+
+    INTEGER, INTENT(in) :: search_type  !< Type of search operation
+           ! 0: Search routine of PDAF 3.0
+           ! 1: Optimized search code
+           ! 2: Optimized search code with only one search loop (default)
+           ! 11: Search type using sorted observations
+           ! 12: Search type using sorted observations with only one search loop
+           ! 21: Search type using sorted observations with a computed upper loop limit
+           ! 22: Search type using sorted observations with a computed upper loop limit 
+           !       and only one search loop
+           !<  (2, 12 and 22 need more memory as arrays are allocated with full observation dimension)
+    INTEGER, INTENT(in) :: sortdir         !< Sorted doordinate direction (default=2)
+}}}
+
+For more information see the [wiki:PDAFomi_set_searchtype Page on PDAFomi_set_searchtype].
+
+
 == Determining observation localization weights ==