Changes between Version 27 and Version 28 of ImplementAnalysisletkf

Timestamp:

Jun 4, 2025, 10:30:54 AM (2 days ago)

Author:

lnerger

Comment:

--

ImplementAnalysisletkf

@@ -42 +42 @@
 == Overview ==
 
-For the analysis step of the LETKF algorithm, several operations related to the observations are needed. These operations are requested by PDAF by calling user-supplied routines. Intentionally, the operations are split into separate routines in order to keep the operations rather elementary as this procedure should simplify the implementation. The names of the required routines are specified in the call to the routine `PDAF_assimilate_letkf` in the fully-parallel implementation (or `PDAF_put_state_letkf` for the 'flexible' implementation) described below. With regard to the parallelization, all these routines (except `U_collect_state`) are executed by the filter processes (`filterpe=.true.`) only.
+The LETKF (Local Ensemble Transform Kalman Filter, Hunt et al., 2007) is a widely used ensemble square-root Kalman filter. For the analysis step of the LETKF algorithm, several operations related to the observations are needed. These operations are requested by PDAF by calling user-supplied routines. Intentionally, the operations are split into separate routines in order to keep the operations rather elementary as this procedure should simplify the implementation. The names of the required routines are specified in the call to the routine `PDAF_assimilate_letkf` in the fully-parallel implementation (or `PDAF_put_state_letkf` for the 'flexible' implementation) described below. With regard to the parallelization, all these routines (except `U_collect_state`) are executed by the filter processes (`filterpe=.true.`) only.
 
 For completeness we discuss here all user-supplied routines that are specified in the interface to `PDAF_assimilate_letkf`. Many of the routines are localized versions of those that are needed for the global ETKF method. Hence, if the user-supplied routines for the global ETKF method have been already implemented, one can base on these routines to speed up the implementation. Due to this, it can also be reasonable to first fully implement a global filter version and subsequently implement the corresponding localized filter by modifying and extending the global routines.
 
-The LSEIK filter and the LETKF (Local Ensemble Transform Kalman Filter) are very similar. For this reason, the interface to the user-supplied routines is almost identical. Depending on the implementation it can be possible to use identical routines for the LSEIK filter and the LETKF. Differences are marked in the text below. 
+The LESTKF and the LETKF are very similar. For this reason, the interface to the user-supplied routines is almost identical. Depending on the implementation it can be possible to use identical routines for the LESTKF filter and the LETKF. Differences are marked in the text below. 
 
 == `PDAF_put_state_letkf` ==