ARPEGE Model analyzed fields

Data set description
Model analysis selection page

Description: ARPEGE is a variable resolution spectral primitive equation system, run with a semi-Lagrangian semi-implicit scheme. At the time of the field phase of the experiment, the model was run with 27 vertical levels and a T149 horizontal resolution and a stretching factor 3.5, corresponding to a T300 averaged resolution over the Atlantic and a T400 resolution over western Europe.

The set of ARPEGE analyzed fields available in the FASTEX Central Archive corresponds to the data assimilation suite run operationally at Meteo-France during the campaign, with a scheme based on the Optimal Interpolation formalism.

Spatial coverage and resolution: Global grid, latitude X longitude, resolution 1.5 degrees, poles excluded.
Vertically : 24 pressure levels.
This resolution appears as a reasonable compromise between what the model can represent and what the data distribution is representative of.

Temporal coverage and resolution: January and February 97 will be entirely covered (60 days), frequency 6 hours.

4D-Var data set: Since the field phase of the experiment, a new data set of analyses has been built from a complete reanalysis of the FASTEX period with a 4D-Var scheme. This scheme has become the operational assimilation system at Meteo-France, since July 2000. Apart from the difference in the assimilation formalism, these new analyses also differ from the operational ones by the fact that they use the TOVS radiances directly (without preliminary inversion) and that the resolution has been increased: 31 levels and a T199 spectral resolution on the stretched sphere.

The 4D-Var analyses are available in a GRIB or ARPEGE format upon request. This allows to better fulfill users' specifications on the resolution or the type of the retrieved fields.

Data set in the FASTEX Central Archive:

  • Model analyzed fields provided by Gerald Desroziers and Beatrice Pouponneau Meteo-France, CNRM/GMME
  • first set of operational analyses : available since summer 1997
  • 2nd set of 4D-Var re-analyses : available upon request to

  • Dated: 5 November 2002