Home > User’s guide > 11. Data assimilation > 11.4 Nature > ISBA: EKF soil assimilation ISBA: EKF soil assimilation

Latest update : 13 May 2016.

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

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 package contains example files to run SODA-EKF in SURFEX V8:

GZ - 72.1 kb

Documentation is available in the package. It was finalized by David Fairbairn and Simon Munier.

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SURFEX (académie de Versailles)