Presentation of Claude Fischer, Andras Horanyi and Wafaa Sadiki during the ALATNET training course on Data Assimilation in Gourdon, 11-22 June 2001.

Contents :

• General aspects :
  • motivations
  • history
  • general formulation of the cost function
  • error covariance matrices
  • minimization algorithms
• Practical implementation : where the problems start and where refinements are needed
  • (multi-)incremental approach
  • quasi-continuous approach
  • the exemple of Météo-France 4D-Var
  • flow dependant structure function
• Limited Area and Lateral Boundary Coupling
  • scale selection and localisation
  • possible tools
  • nested assimilation cycles
  • boundaries and coupling in 4D-Var