1.Ensemble version
Ensemble identifier code: SEAS5
Research or operational: Operational
First operational forecast run: 1 November 2017
2. Configuration of the forecast model
Is the model coupled to an ocean model? Yes from day 0
Coupling frequency: 1 hour
2.1 Atmosphere and land surface
Model | IFS Cycle 43r1 |
---|---|
Horizontal resolution and grid | Dynamics:TCO319 Cubic octahedral grid Physics: O320 Gaussian grid (36 km) |
Atmosphere vertical resolution | L91 (0.01 hPa) |
Top of atmosphere | 0.01 hPa (approx. 80 km) |
Soil levels | 4 |
Time step | 20 minutes |
Detailed documentation: IFS cycle 43r1 documentation
2.1 Ocean and cryosphere
Ocean model | NEMO v3.4 |
---|---|
Horizontal resolution | ORCA 0.25 |
Vertical resolution | L75 |
Time step | 1 hour |
Sea ice model | LIM2 |
Sea ice model resolution | ORCA 0.25 |
Sea ice model levels | 1 |
Wave model | ECMWF wave model |
Wave model resolution | 0.5 degrees |
Detailed documentation:
3. Initialization and initial condition (IC) perturbations
3.1 Atmosphere and land
Re-forecast | Forecast | |
---|---|---|
Atmosphere initialization | ERA-Interim | ECMWF Operations |
Atmosphere IC perturbations | Ensemble data assimilation and leading singular vectors applied to upper air variables | Ensemble data assimilation and leading singular vectors applied to upper air variables |
Land Initialization | ERA-Interim land (43r1) | ECMWF Operations |
Land IC perturbations | Ensemble data assimilation applied to some land fields | Ensemble data assimilation applied to some land fields |
Soil moisture initialization | ERA-Interim land | ECMWF operations |
Snow initialization | ERA-Interim land | ECMWF operations |
Unperturbed control forecast? | Yes | Yes |
Detailed documentation: IFS cycle 43r1 documentation and seas5 user guide
Data assimilation method for control analysis: 4D Var (atmosphere) and 3DVAR (ocean/sea-ice)
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-forecast | Forecast | |
---|---|---|
Ocean initialization | ORAS5 | ORTA5 |
Ocean IC perturbations | Yes - generated through perturbations to assimilated observations and surface forcing | Yes - generated through perturbations to assimilated observations and surface forcing |
Unperturbed control forecast? | No | No |
Ocean data assimilation details? References?
Source and treatment of SST? (Other data sources - altimetry?)
4. Model Uncertainties perturbations:
Model dynamics perturbations | No |
---|---|
Model physics perturbations | 3-lev SPPT and SPBS |
If there is a control forecast, is it perturbed? | Yes |
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 years | 36 (1981-2016) |
Re-forecast ensemble size | 25 (LR) 15 (AR) |
Calibration (bias correction) period | 1993-2016 |
6. References
More details and references here.