Page tree
Skip to end of metadata
Go to start of metadata

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

Coupling frequency: 1 hour

2.1 Atmosphere and land surface

ModelIFS Cycle 43r1
Horizontal resolution and grid

Dynamics:TCO319 cubic octahedral grid

Physics: O320 Gaussian grid (36 km)

Atmosphere vertical resolutionL91
Top of atmosphere0.01 hPa (approx. 80 km)
Soil levels4
Time step20 minutes

Detailed documentation: IFS cycle 43r1 documentation

2.2 Ocean and cryosphere

Ocean model

NEMO v3.4

Horizontal resolutionORCA 0.25
Vertical resolutionL75
Time step1 hour
Sea ice modelLIM2
Sea ice model resolutionORCA 0.25
Sea ice model levelsN/A
Wave modelECMWF wave model
Wave model resolution0.5 degrees

Detailed documentation: NEMO documentation and IFS cycle 43r1 documentation

3. Initialization and initial condition (IC) perturbations

3.1 Atmosphere and land


HindcastForecast
Atmosphere initialization
ERA-InterimECMWF operations
Atmosphere IC perturbationsEnsemble data assimilation and leading singular vectors applied to upper air variablesEnsemble 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)ECMWF operations
Land IC perturbationsEnsemble data assimilation applied to some land fieldsEnsemble data assimilation applied to some land fields
Soil moisture initialization43r1 land surface model driven by ERA-Interim (like ERA-Interim land)ECMWF operations
Snow initialization43r1 land surface model driven by ERA-Interim (like ERA-Interim land)ECMWF operations
Unperturbed control forecast?YesYes

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

Detailed documentation: IFS cycle 43r1 documentation and SEAS5 user guide


3.2 Ocean and cryosphere


HindcastForecast
Ocean initializationORAS5ORTA5
Ocean IC perturbations Yes - generated through perturbations to assimilated observations and surface forcingYes - generated through perturbations to assimilated observations and surface forcing
Unperturbed control forecast?NoNo

Detailed documentation: ECMWF ocean reanalysis documentation and SEAS5 user guide


4. Model Uncertainties perturbations:

Model dynamics perturbationsNo
Model physics perturbations3-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 years36 (1981-2016)
Hindcast ensemble size

25 (LR)

15 (AR)

On-the-fly or static hindcast set?static

6. Where to find more information

ECMWF seasonal forecast documentation page


  • No labels