Two century of data assimilation

  • End of the XVIIIth century:

    • Planet orbit computations by Gauss

    • Least square method by Legendre

  • Begining of the XXth century:

    • Concept of maximum likelyhood by Fisher

  • Mid of the XXth century:

    • Kalman filter for the APOLLO program

    • Objective analysis of meteorological fields

  • End of the XXth century:

    • 3D-var data assimilation method for weather forecast model

    • Gain of 20% forecast quality at Météo-France going to 4D-var