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ALADIN documentation / 3DVAR aspects, 2007 updated

November 2002

This note gives a detailed description of the algorithmic part, for the benefit of phasing, remote installations and development. A theoretical overview is recalled for completeness with the technical section. A "User’s guide" is added for the general users of 3dvar.

Formalism of incremental variational analysis
- 3dvar
- Background error covariance matrix B
- Preconditioning
- 4dvar
Data flow and code organisation
- Screening
- 3dvar minimisation
- 4dvar minimisation
User’s guide : scripts and namelists
- Sequences of execution and Input/Output
- Most important namelist parameters
- How to check for the execution ?
- Frequently encountered ... crashes
Domain definitions in ALADIN
Aspects of the data distribution on MPP machines