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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 |
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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 |
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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 | |
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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 |
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Detailed documentation: IFS cycle 43r1 documentation and SEAS5 user guide
3.2 Ocean and cryosphere
Hindcast | Forecast | |
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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 |
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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) | ||
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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