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 | N/A |
| Wave model | ECMWF wave model |
| Wave model resolution | 0.5 degrees |
Detailed documentation: NEMO documentation and IFS cycle 43r1 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
More DA details?
Data assimilation method for control analysis: 4D Var (atmosphere) and 3DVAR (ocean/sea-ice)
Horizontal and vertical resolution of perturbations: T42L91 SVs+ T399L137 EDA perturbations
Perturbations in +/- pairs: Yes
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 |
Detailed documentation: ECMWF ocean reanalysis documentation and SEAS5 user guide
Ocean data assimilation details? 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 |
Detailed documentation: IFS cycle 43r1 documentation
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) |
| On-the-fly or static re-forecast set? | static |
| Calibration (bias correction) period | 1993-2016 |
6. References
More details and references here.
