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

1. Forecast system version

System name: GCFS 2.0

First operational forecast run: April 2018

2. Configuration of the forecast model

Is it a coupled model?  Yes

Coupling frequency: 1 hour

2.1 Atmosphere and land surface

Model

ECHAM 6.3.04 (atmosphere)

JSBACH (land)

Horizontal resolution and gridT127 (~100 km) on regular Gaussian grid
Atmosphere vertical resolutionL95
Top of atmosphere0.01 hPa
Soil levels

5

Level 1: 0 - 0.065 m

Level 2: 0.065 - 0.319 m

Level 3: 0.319 - 1.232 m

Level 4: 1.232 - 4.134 m

Level 5: 4.134 - 9.834 m

Time step200 s

Detailed documentation:

ECHAM6: Stevens et al., 2013

Soil scheme: Hagemann and Stacke, 2014

Runoff scheme: HD Hagemann and Dümenil-Gates, 2003


2.2 Ocean and cryosphere

Ocean model

MPIOM 1.6.3

Horizontal resolutionTP04 (0.4°) on a tripolar grid
Vertical resolutionL40
Time step1 h
Sea ice modelThermodynamic and sea-ice dynamics
Sea ice model resolutionsame as ocean model
Sea ice model levelszero-layer model
Wave modelNA
Wave model resolutionNA

Detailed documentation: MPIOM: Jungclaus et al., 2013

3. Initialization and initial condition (IC) perturbations

3.1 Atmosphere and land


HindcastForecast
Atmosphere initialization
ERA-InterimECMWF operations
Atmosphere IC perturbationsnonenone

Land Initialization

indirect via atmosphere initializationindirect via atmosphere initialization
Land IC perturbationsnonenone
Soil moisture initializationindirect via atmosphere initializationindirect via atmosphere initialization
Snow initializationindirect via atmosphere initializationindirect via atmosphere initialization
Unperturbed control forecast?yesyes

The assimilation for the atmosphere employs Newtonian relaxation of the reference data with the following variable-dependent relaxation times:

  • divergence (48 hrs)
  • vorticity (6hrs)
  • temperature (~4hrs)
  • logarithm of surface pressure (~4 hrs)

Data assimilation method for control analysis: no ensemble data assimilation


3.2 Ocean and cryosphere


HindcastForecast
Ocean initializationORAS5ORAS5
Ocean IC perturbations

The very first hindcast ensemble in 1990 starts with lagged initialisation of the 30 members by each one day.

Subsequently, bred vectors add small disturbances to the global three-dimensional ocean temperature and salinity fields

bred vectors add small disturbances to the global three-dimensional ocean temperature and salinity fields

Unperturbed control forecast?yesyes

More ocean data assimilation details:

  • Assimilation of 3D temperature and salinity (ORAS5 data) using Newtonian relaxation with ~10 days of relaxation time
  • Assimilation of sea-ice concentration (ORAS5 data) using Newtonian relaxation with ~20 days of relaxation time

Detailed documentation: GCFS ocean data assimilation: Baehr & Piontek, 2014


4. Model uncertainties perturbations:

Model dynamics perturbationsno
Model physics perturbationsatmosphere: perturbation of diffusion in uppermost layer

If there is a control forecast, is it perturbed?

unperturbed control forecast

Detailed documentation: Baehr et al. (2015)

5. Forecast system and hindcasts


Forecast frequencymonthly
Forecast ensemble size50
Hindcast years1993 - 2017
Hindcast ensemble size30
On-the-fly or static hindcast set?static


6. Other relevant information

The forcing database for radiative parameters like ozone, aerosol and greenhouse gases is provided by CMIP6 for the historical period up to 2014. Afterwards, values are kept constant as CMIP6 future scenarios were not yet available.

7. Where to find more information

www.dwd.de/seasonalforecasts


 

  • No labels