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The AROME RUC (presentation, March 2008)
Article published on 31 March 2008

by Patricia

Presentation of Pierre Brousseau during the 2nd AROME training course, Lisbon, 4-7 March 2008 : "A mesoscale data assimilation system for operations : the AROME RUC", PierreBrousseau, Y. Seity, L. Auger, L.Berre, T.Montmerle, E. Wattrelot, C. Faccani


  • General ideas on data assimilation
  • The AROME data assimilation system
  • Background-error Statistics
  • Assimilation experiments


  • A prototype for the AROME data assimilation system is currently being tested at Météo-France.
    (* It is supplied by the same kind of observation as the ALADIN-FRANCE operational suite.
  • The background-error statistics for AROME have been calculated by an ensemble methode using the same multivariate formulation as in ALADIN-France. Compared to the ALADIN-FRANCE ones, background-error standard deviations are increased and horizontal correlation length scales are much shorter: Analysis increments are strongerand narrower.
  • This prototype shows its ability to improve analysis and forecasts, giving a more realistic depiction of initial conditions.
  • The general benefit of the analysis appears during the first 12-hour forecast ranges, then lateral conditions mostly takeover the model solution.


  • Works currently in progress on :
    • the use of observations at a higher spatial resolution (airep, IR radiances,…).
    • the assimilation of observations more representative of mesoscale like RADAR winds and reflectivities (see also the talk of Eric Wattrelot).
    • A surface assimilation for AROME (see also the talk of Rafiq Hamdi).
  • Works are planned in orderto takea better advantageof high-frequencyobservations using:
    • 3D-FGAT (First Guess at Appropriate Time) assimilation scheme
    • Incremental Digital Filter Initialization allowing 1-h cycling
  • AROME schedule :
    • April 2008 : AROME pre-operational suite managed by operational team (3-h RUC, RADAR winds,…).
    • October 2008 : AROME declared operational at Meteo-France (?)