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
| Model | IFS Cycle 43r1 |
|---|---|
| Horizontal resolution | TCO319/ O320 Gaussian grid (35 km) |
| Model grid type | Cubic octahedral grid |
| Vertical resolution (TOA) | L91 (0.01 hPa) |
| Time step |
Detailed documentation:
2.1 Ocean and cryosphere
| Ocean model | NEMO v3.4 |
|---|---|
| Horizontal resolution | ORCA 0.25 |
| Vertical resolution | L75 |
| Time step | |
| Sea ice model | LIM2 |
| Sea ice model resolution | |
| Sea ice model levels | |
| Wave model | ECMWF wave model |
| Wave model resolution | 0.5 degrees |
Detailed documentation:
3. Initial conditions and perturbations
3.1 Atmosphere
| 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 |
Land Initialization | ERA-Interim land (43r1) | ECMWF Operations |
| Land IC perturbations | ||
| Soil moisture inititialization | ERA-Interim | ECMWF operations |
| Snow initiialization | ERA-Interim | ECMWF operations |
| Unperturbed control forecast? | Yes | Yes |
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 initial conditions
| Re-forecast | Forecast | |
| Ocean initialization | ORAS5 | ORTA5 |
|---|---|---|
| Ocean perturbations | 5 member ensemble created through surface forcing perturbations and | |
| Unperturbed control forecast? |
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? |
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:
