The Extended Kalman Filter (EKF) is an option to be used on several soil properties. At the moment TG1/2, WG1/2 and LAI can be used as control variables. Extended Kalman Filter is activated by setting CASSIM_ISBA="EKF" in NAM_ASSIM:
| Fortran name | Fortran type | values | default value |
| CASSIM_ISBA | CHARACTER | EKF/OI | OI |
Before EKF can be used you have to run the same number of perturbed offline runs as the number of control variables you are using in addition to an unperturbed control run.
This can be set in NAM_IO_VARASSIM:
| Fortran name | Fortran type | values | default value |
| LPRT | logical | F |
When running the assimilation, the initalization is done by reading the total number of perturbed runs (+ the unpertubed) and storing the relevant fields for assimilation in memory. In inline mode an additional reading is done, which ideally should be removed.
NB! At the moment the internal matrices are stored as text files pr. individual CPUs. It means you can not change the number of CPUs used (or control variables) from one cycle to the next unless you start from a "cold" start with no existing matrices.
The following links contain documentation and example files to run SODA-EKF in SURFEX V8.1:
https://opensource.umr-cnrm.fr/projects/openldasmonde/wiki/
https://www.umr-cnrm.fr/spip.php?article1022
Specific namelist for the control variables for EKF.
Fortran name Fortran type values default value NIVAR integer 1 NVAR integer ≤5 4 CVAR_M character(len=5) "WG2", "WG1", "TG2", "TG1" ,"LAI" (...)
Specific namelist for the observations in EKF. For the moment, 5 types of observation are possible: "T2M", "HU2M", "WG1", "LAI" and "SWE".
Fortran name Fortran type values default value NOBSTYPE integer ≤5 2 LOBSHEADER logical (...)
General SODA EKF options. Note that LBEV and LBFIXED are exclusive, and could a priori be reduced to one single logical.
Fortran name Fortran type values default value LSIM logical F LPRT logical F LBEV (...)
For EKF only the time information is used from this namelist.
Fortran name Fortran type values default value NECHGU integer 6 NECHGU : coefficient for OI & number of hours separating 2 observation (...)
General assimilation namelist used only with SODA. Note that NBOUTPUT should be moved in NAM_OBS for more consistency.
Fortran name Fortran type values default value LASSIM logical F CASSIM character(5) "PLUS ","2DVAR" (...)
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