| Table of Contents | ||
|---|---|---|
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1. Forecast system version
Identifier code: SEAS5
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 |
| Top of atmosphere | 0.01 hPa (approx. 80 km) |
| Soil levels (layers) | 4 Layer 1 : 0 - 7 cm |
| Time step | 20 minutes |
Detailed documentation: IFS cycle 43r1 documentation
2.
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2 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
| Hindcast | 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 | 43r1 land surface model driven by ERA-Interim (like 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 | 43r1 land surface model driven by ERA-Interim (like ERA-Interim land) | ECMWF operations |
| Snow initialization | 43r1 land surface model driven by ERA-Interim (like ERA-Interim land) | ECMWF operations |
| Unperturbed control forecast? | Yes | Yes |
...
Detailed documentation: IFS cycle 43r1 documentation and SEAS5 user guide
3.2 Ocean and cryosphere
| Hindcast | 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
4. Model Uncertainties perturbations:
| Model dynamics perturbations | No |
|---|---|
| Model physics perturbations | 3-level SPPT and SPBS |
If there is a control forecast, is it perturbed? | Yes |
Detailed documentation: IFS cycle 43r1 documentation
5. Forecast system and hindcasts
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 latter not available from C3S). 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) | ||
| Hindcast years | 36 (1981-2016) | ||
| Hindcast ensemble size | 25 (LR) 15 (AR) | ||
| On-the-fly or static hindcast set? | static | Calibration (bias correction) period | 1993-2016 |
6. Where to find more information
ECMWF seasonal forecast documentation page