The main characteristics of the COMET-LETKF data assimilation system are:

  • Domain and resolution: the system is running on the Mediterranean-European domain with 40 ensemble members plus a deterministic member, having a 0.0625° grid spacing (~7 km) and 49 vertical levels. The configuration is defined on a rotated regular grid, the coordinates of rotated north pole are (47.0,-10.0).
  • Observations: the observational dataset operationally ingested comprises radiosonde ascents (RAOB), surface pressure observations from land and sea stations (SYNOP, SHIP, BUOY), manual and automatic aircraft observations, atmospheric motion vectors from Meteosat, European wind profilers, scatterometer winds from METOP A-B, NOAA/MetopA-B MSUA/MHS and NPP ATMS radiances.
  • Lateral Boundary conditions: they are from IFS deterministic run perturbed using ECMWF-EPS.
  • Surface perturbations: climatological perturbed sea surface temperature.
  • Model and sampling error: "Relaxation-to-prior spread" multiplicative inflation method according to Whitaker et al. 2012 and additive noise from scaled ECMWF EPS.
  • Assimilated obs. SYNOP, SHIP, BUOY, RAOB (also 4D), PILOT, WIND-PROFILER/RADAR, AIREP, AMDAR, ACAR, MSG3-MET8 AMV, Metop A-B scatt. winds, NOAA-Metop A-B AMSUA/MHS and NPP ATMS radiances
    Assimilation cycle 3 hours
    Analysis method LETKF
    background 3 hours COSMO forecasts
    Coverage Mediterranean European region (Fig)
    Horizontal resolution 0.0625° x 0.0625°
    Vertical resolution 49 model levels
    Model and sampling error "Relaxation-to-prior spread" multiplicative inflation method according to Whitaker et al. 2012
    Additive noise from scaled ECMWF EPS pertubations
    Lateral and surface BCs perturbation Lateral Boundary conditions from the most recent IFS deterministic run perturbed using ECMWF EPS Climatologically perturbed SST

    References:Whitaker, J. S. and Hamill, T. M. 2012. Evaluating methods to account for system errors in ensemble data assimilation. Mon. Wea. Rev. 140, 3078_3089.