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1.Ensemble version

Ensemble identifier code: SEAS5

Research or operational: Operational

First operational forecast run: 1 November 2017

2. Configuration of the EPS

Is the model coupled to an ocean model?   Yes from day 0

Coupling frequency: 1 hour

2.1 Atmosphere and land surface

ModelIFS Cycle 43r1
Horizontal resolution and grid

Dynamics:TCO319 Cubic octahedral grid

Physics: O320 Gaussian grid (35 km)

Atmosphere vertical resolutionL91 (0.01 hPa)
Top of atmosphere0.01 hPa (approx. 80 km)
Soil levels
Time step20 minutes

Detailed documentation: IFS cycle 43r1 documentation

2.1 Ocean and cryosphere

Ocean model

NEMO v3.4

Horizontal resolutionORCA 0.25
Vertical resolutionL75
Time step1 hour
Sea ice modelLIM2
Sea ice model resolution
Sea ice model levels
Wave modelECMWF wave model
Wave model resolution0.5 degrees

Detailed documentation:

3. Initialization and initial condition (IC) perturbations

3.1 Atmosphere and land


Re-forecastForecast
Atmosphere initialization
ERA-InterimECMWF Operations
Atmosphere IC perturbationsEnsemble data assimilation and leading singular vectors applied to upper air variablesEnsemble data assimilation and leading singular vectors applied to upper air variables

Land Initialization

ERA-Interim land (43r1)ECMWF Operations
Land IC perturbationsEnsemble data assimilation and leading singular vectors applied to some land fieldsEnsemble data assimilation and leading singular vectors applied to some land fields
Soil moisture initializationERA-InterimECMWF operations
Snow initializationERA-InterimECMWF operations
Unperturbed control forecast?YesYes

Detailed documentation: IFS cycle 43r1 documentation

Data assimilation method for control analysis: 4D Var (atmosphere) and 3DVAR (ocean/sea-ice)

Resolution of model used to generate Control Analysis: TL1279L137

Ensemble initial perturbation strategy: Singular vectors + Ensemble Data Assimilation perturbations added to control analysis

Horizontal and vertical resolution of perturbations:  T42L91 SVs+ T399L137 EDA perturbations

Perturbations in +/- pairs: Yes

Perturbations to sea surface temperature? Yes (5-member ensemble of ocean analyses/re-analyses)

3.2 Ocean and cryosphere


Re-forecastForecast
Ocean initializationORAS5ORTA5
Ocean IC perturbations Yes - generated through perturbations to assimilated observations and surface forcingYes - generated through perturbations to assimilated observations and surface forcing
Unperturbed control forecast?NoNo

4. Model Uncertainties perturbations:

Model dynamics perturbationsNo
Model physics perturbations3-lev SPPT and SPBS
If there is a control forecast, is it perturbed?

5. Forecast system and re-forecasts

Note, the ECMWF seasonal forecasts cover two time ranges: the long range (LR) forecasts out to 7 months, and annual range (AR) forecasts out to 13 months. The model used for these forecasts is identical, but they have different numbers of forecast members.

Forecast frequency

monthly (LR)

quarterly (AR)

Forecast ensemble size

51 (LR)

15 (AR)

Re-forecast years36 (1981-2016)
Re-forecast ensemble size

25 (LR)

15 (AR)

Calibration (bias correction) period1993-2016

6. References

More details and references here.

 

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