1. Ensemble version



Ensemble identifier codeCNRM-CM 6.1CNRM-CM 6.0
Short Description

CNRM-CM6.1 (Voldoire et al. 2019) global ensemble generated with perturbed atmospheric initial conditions.

Based on 25 members and run once a week (every Thursday) up to day 47

Global ensemble system that simulates model uncertainties using a stochastic scheme. Based on 51 members

Before 1/3/2016 (excluded):  run once a month (Day 1 of calendar month at 00Z) up to day 61

After 1/3/2016  (included) :   run once a week (every Thursday) up to day 32 (weekly runs before 1/3/2016 are available at meteo-France)

Research or operationalResearchResearch
Data time of first forecast run22/10/202001/04/2015

2. Configuration of the EPS



Is the model coupled to an ocean model?   Yes from day 0Yes from day 0
If yes, please describe ocean model briefly including frequency of coupling and any ensemble perturbation applied.Ocean model is NEMO3.6 with a 0.25 degree horizontal resolution, 75 vertical levels, initialized from unperturbed MERCATOR-OCEAN Ocean and Sea-ice Analysis. Frequency of coupling is hourly.Unperturbed MERCATOR-OCEAN Ocean and Sea-ice Analysis. Frequency of coupling is 24-hourly.
If no, please describe the sea surface temperature boundary conditions (climatology, reanalysis ...) 
Is the model coupled to a sea Ice model?YesYes
If yes, please describe sea-ice model briefly including any ensemble perturbation applied.Sea-ice model is GELATO v6 , embedded in the ocean model. It is initialized from unperturbed 0.25 degree resolution MERCATOR-OCEAN Ocean and Sea-ice AnalysisSea-ice model is GELATO v5 , embedded in the ocean model. It is initialized from unperturbed 1 degree resolution MERCATOR-OCEAN Ocean and Sea-ice Analysis
Is the model coupled to a wave model?NoNo
If yes, please describe wave model briefly including any ensemble perturbation appliedN/AN/A
Ocean modelNEMO 3.6 0.25 degree resolutionNEMO 1 degree resolution
Horizontal resolution of the atmospheric modelTL359 (about 50 km)TL255 (about 80 km)
Number of model levels9191
Top of model0.01 hPa0.01 hPa
Type of model levelshybrid sigma-pressurehybrid sigma-pressure
Forecast length46 days61 days (1464 hours)
Run FrequencyOnce a weekOnce a week since March 2016 (once a month (Day 1 of calendar month at 00Z) before March 2016)
Is there an unperturbed control forecast included?NoNo
Number of perturbed ensemble members2551
Integration time step10 minutes15 minutes

3. Initial conditions and perturbations



Data assimilation method for control analysis4D Var4D Var
Resolution of model used to generate Control AnalysisO1280 IFS HRES operational analysis TL1279L137 (IFS operational analysis)
Ensemble initial perturbation strategyNone (in-run perturbations only)None (in-run perturbations only)
Horizontal and vertical resolution of perturbationsN/AN/A
Perturbations in +/- pairsN/AN/A
Initialization of land surface

3.1 What is the land surface model (LSM) and version used in the forecast model, and what are the current/relevant references for the model?ISBA-CTRIB, embedded into SURFEX 8.0 numerical interface (Decharme et al. 2019) SURFEX 7.2
     Are there any significant changes/deviations in the operational version of the LSM from the documentation of the LSM?NoNo
3.2 How is soil moisture initialized in the forecasts? (climatology / realistic / other) realisticrealistic
     If “realistic”, does the soil moisture come from an analysis using the same LSM as is coupled to the GCM for forecasts, or another source? Please describe the process of soil moisture initialization.It comes from ECMWF HRES analyses (ERA5 for the re-forecast)It comes from ECMWF analyses
     Is there horizontal and/or vertical interpolation of initialization data onto the forecast model grid? If so, please give original data resolution(s). Yes for horizontal, original resolution is 9km, final resolution is 50 kmYes for horizontal, original resolution is 9km, final resolution is 70 km
     Does the LSM differentiate between liquid and ice content of the soil? If so, how are each initialized?Yes, liquid and ice are determined by temperature Yes, liquid and ice are determined by temperature
      If all model soil layers are not initialized in the same way or from the same source, please describe. The method to interpolate between ECMWF soil layers and SURFEX soil layers is described in Boisserie et al. (2016)The method to interpolate between ECMWF soil layers and SURFEX soil layers is described in Boisserie et al. (2016)
3.3 How is snow initialized in the forecasts? (climatology / realistic / other) realisticrealistic
     If “realistic”, does the snow come from an analysis using the same LSM as is coupled to the GCM for forecasts, or another source? Please describe the process of soil moisture initialization. It comes from ECMWF analysesIt comes from ECMWF analyses
      Is there horizontal and/or vertical interpolation of data onto the forecast model grid? If so, please give original data resolution(s) Yes for horizontal, original resolution is 9 km, final resolution is 70 kmYes for horizontal, original resolution is 9 km, final resolution is 70 km
      Are snow mass, snow depth or both initialized? What about snow age, albedo, or other snow properties? Snow mass only is initialized. Snow density and albedo are initialized with characteristics of old snow, and then evolve with the modelSnow mass only is initialized. Snow density and albedo are initialized with characteristics of old snow, and then evolve with the model
3.4. How is soil temperature initialized in the forecasts? (climatology / realistic / other) realisticrealistic
     If “realistic”, does the soil moisture come from an analysis using the same LSM as is coupled to the GCM for forecasts, or another source? Please describe the process of soil moisture initialization.It comes from ECMWF analysesIt comes from ECMWF analyses
     Is the soil temperature initialized consistently with soil moisture (frozen soil water where soil temperature ≤0°C) and snow cover (top layer soil temperature ≤0°C under snow)? Yes Yes
     Is there horizontal and/or vertical interpolation of data onto the forecast model grid? If so, please give original data resolution(s) Yes for horizontal, original resolution is 9 km, final resolution is 50 kmYes for horizontal, original resolution is 9 km, final resolution is 70 km
     If all model soil layers are not initialized in the same way or from the same source, please describe. See Boisserie et al. (2016)See Boisserie et al. (2016)
3.5. How are time-varying vegetation properties represented in the LSM? Monthly climatology (Ecoclimap, Masson et al. 2003)Monthly climatology (Ecoclimap, Masson et al. 2003)
3.6. What is the source of soil properties (texture, porosity, conductivity, etc.) used by the LSM? HWSD (Harmonized World Soil Database)Ecoclimap, Masson et al. (2003)
3.7 If the initialization of the LSM for re-forecasts deviates from the procedure for forecasts, please describe the differences. The procedure is identical. The source is ERA5 instead of operational HRES ECMWF analyses.The procedure is identical. The source is ERA-interim instead of operational ECMWF.

4. Model Uncertainties perturbations



Is model physics perturbed?NoNo
Do all ensemble members use exactly the same model version?YesYes
Is model dynamics perturbed? Yes (Batté and Déqué 2016)Yes (Batté and Déqué 2012)
Are the above model perturbations applied to the control forecast? YesYes
 Additional Commentssee Referencessee References

5. Surface Boundary perturbations



Perturbations to sea surface temperature?NoNo
Perturbation to soil moisture?NoNo
Perturbation to surface stress or roughness?NoNo
Any other surface perturbation?NoNo
Are the above surface perturbations applied to the Control forecast?N/AN/A
Additional comments

6. Other details of the models



Description of model gridReduced Gaussian GridReduced Gaussian Grid
List of model levels in appropriate coordinateshttp://www.ecmwf.int/en/forecasts/documentation-and-support/91-model-levelshttp://www.ecmwf.int/en/forecasts/documentation-and-support/91-model-levels
What kind of large scale dynamics is used?  Spectral semi-lagrangianSpectral semi-lagrangian
What kind of boundary layer parameterization is used? Turbulence : Cuxart et al 2000Ricard and Royer 93
What kind of convective parameterization is used? Piriou et al (2007), Guérémy (2011)Bougeault 85
What kind of large-scale precipitation scheme is used? Lopez 2002Smith 90
What cloud scheme is used? Lopez 2002Ricard and Royer 93
What kind of land-surface scheme is used? ISBAdf-CTRIPISBA-3L
How is radiation parametrized?

     Long Wave RadiationRapid Radiation Transfer Model (RRTM), Mlawer et al 1997Rapid Radiation Transfer Model (RRTM)
     Short Wave radiationFouquart and Bonnel (1980)Foucart-Morcrette
Sea-ice thicknessAverage sea-ice thickness (computed only where there is sea-ice)
Other relevant details? See ReferencesSee References

7. Re-forecast Configuration



Number of years covered25 years (1993-2017)22 years (1993-2014)
Produced on the fly or fix re-forecasts? Fix re-forecastsFix re-forecasts
FrequencyThe re-forecast consists of a 10-member ensemble starting every Thursday from 31 Dec 1992 till 28 Dec 2017The re-forecast  consists of a 15-member ensemble starting the 1st, 8th, 15th and 22nd calendar day of each month for the period 1993-2014
Ensemble size10 members15 members
Initial conditionsERA5(31km) for Atmosphere and Land surface + MERCATOR-OCEAN ocean reanalyses (0.25 degree)ERA interim (T255L60) for Atmosphere and Land surface + MERCATOR-OCEAN ocean reanalyses (1 degree)
Is the model physics and resolution  the same as for the real-time forecastsYesYes
If not, what are the differencesN/AN/A
Is the ensemble generation the same as for real-time forecasts?YesYes
If not, what are the differencesN/AN/A

8. References

  • Batté, L. and Déqué, M. (2016), ‘Randomly correcting model erros in the ARPEGE-Climate v6.1 component of CNRM-CM : applications for seasonal forecasts.’ Geoscientific Model Development 9(6)
  • Boisserie, M., Decharme, B., Descamps, L. and Arbogast, P. (2016), ‘Land surface initialization strategy for a global reforecast dataset’, Quarterly Journal of the Royal Meteorological Society 142(695), 880–888.
  • Cuxart, J., Bougeault, P. and Redelsperger, J.-L. (2000), ‘A turbulence scheme allowing for mesoscale and large-eddy simulations’, Quarterly Journal of the Royal Meteorological Society 126(562), 1–30.
  • Constantin Ardilouze, Damien Specq, Lauriane Batté, and Christophe Cassou: Flow dependence of wintertime subseasonal prediction skill over Europe, Weather Clim. Dynam., 2, 1033–1049, 2021, https://doi.org/10.5194/wcd-2-1033-2021
  • Decharme, B., Delire, C., Minvielle, M., Colin, J., Vergnes, J.-P., Alias, A., Saint-Martin, D., Séférian,R., Sénési, S. and Voldoire, A. (2019), ‘Recent changes in the ISBA-CTRIP land surface system foruse in the CNRM-CM6 climate model and in global off-line hydrological applications’, Journal of Advances in Modeling Earth Systems .
  • Faroux, S., Kaptué Tchuenté, A., Roujean, J.-L., Masson, V., Martin, E. and Moigne, P. L. (2013), ‘ECOCLIMAP-II/Europe : A twofold database of ecosystems and surface parameters at 1 km resolution based on satellite information for use in land surface, meteorological and climate models’, Geoscientific Model Development 6(2), 563–582.
  • Fouquart, Y. and Bonnel, B. (1980), ‘Computations of solar heating of the earth’s atmosphere- A new parameterization’, Beitraege zur Physik der Atmosphaere 53, 35–62.
  • Guérémy, J. (2011), ‘A continuous buoyancy based convection scheme : one-and three-dimensional validation’, Tellus A : Dynamic Meteorology and Oceanography 63(4), 687–706.
  • Lopez, P. (2002), ‘Implementation and validation of a new prognostic large-scale cloud and precipitation scheme for climate and data-assimilation purposes’, Quarterly Journal of the Royal Meteorological Society 128(579), 229–257.
  • Mlawer, E. J., Taubman, S. J., Brown, P. D., Iacono, M. J. and Clough, S. A. (1997), ‘Radiative transfer for inhomogeneous atmospheres : RRTM, a validated correlated-k model for the longwave’, Journal of Geophysical Research : Atmospheres 102(D14), 16663–16682.
  • Piriou, J.-M., Redelsperger, J.-L., Geleyn, J.-F., Lafore, J.-P. and Guichard, F. (2007), ‘An approach for convective parameterization with memory : Separating microphysics and transport in grid-scale equations’, Journal of the Atmospheric Sciences 64(11), 4127–4139.
  • Voldoire, A., Saint-Martin, D., Sénési, S., Decharme, B., Alias, A., Chevallier, M., Colin, J., Guérémy, J.-F., Michou, M., Moine, M.-P., Nabat, P., Roehrig, R., Salas y Mélia, D., Séférian, R., Valcke, S., Beau,I., Belamari, S., Berthet, S., Cassou, C., Cattiaux, J., Deshayes, J., H. Douville, H., Franchisteguy,L., Ethé, C., Geoffroy, O., Lévy, C., Madec, G., Meurdesoif, Y., Msadek, R., Ribes, A., Sanchez, E.,Terray, L. and Waldman, R. (2019), ‘Evaluation of CMIP6 DECK experiments with CNRM-CM6-1’,Journal of Advances in Modeling Earth Systems.
  • URL: http ://www.umr-cnrm.fr/cmip6/references