1. Forecast system version
System name: GloSea5-GC2
First operational forecast run: 3 February 2015
2. Configuration of the forecast model
Is it a coupled model? Yes: Atmosphere, land, ocean and sea-ice.
Coupling frequency: 3-hourly coupling between atmosphere-land and ocean--sea-ice.
(Better use more specific question? Here or elsewhere?)
The coupled model Global Coupled 2 (GC2) is described in Williams et al, 2015.
2.1 Atmosphere and land surface
Model | Met Office Unified Model (UM) - Global Atmosphere 6.0 Joint UK Land Environment Simulator (JULES) - Global Land 6.0 |
---|---|
Horizontal resolution and grid | N216: 0.83 degrees x 0.56 degrees (approx 60km in mid-latitudes) |
Atmosphere vertical resolution | 85 levels |
Top of atmosphere | 85km |
Soil levels | 4 Level 1 : 0 - 0.1 m Level 2 : 0.1 - 0.35 Level 3 : 0.35 - 1.0 m Level 4 : 1.0 - 3.0 m |
Time step | 15 minutes |
Detailed documentation:
Global Atmosphere 6.0 & Global Land 6.0: Walters et al, 2017
More model details? (e.g. land surface model?)
2.1 Ocean and cryosphere
Ocean model | NEMO v3.4 - Global Ocean 5.0 |
---|---|
Horizontal resolution | ORCA 0.25 |
Vertical resolution | L75 |
Time step | 22.5 minutes |
Sea ice model | CICE v4.1 - Global Sea-Ice 6.0 |
Sea ice model resolution | ORCA 0.25 |
Sea ice model levels | 5 categories + open water |
Wave model | N/A |
Wave model resolution | N/A |
Detailed documentation: NEMO documentation, CICE documentation
Global Ocean 5.0: Megann et al, 2014
Global Sea Ice 6.0: Rae et al, 2015.
CM:The sea-ice model has different categories of sea-ice it's not quite the same as levels. It's more like fractions of functional types.
3. Initialization and initial condition (IC) perturbations
3.1 Atmosphere and land
Re-forecast | Forecast | |
---|---|---|
Atmosphere initialization | ERA-Interim | Met Office Global Hybrid 4D-VAR |
Atmosphere IC perturbations | None | None |
Land Initialization | Climatology/ERA-Interim | Climatology/Met Office Global Hybrid 4D-VAR |
Land IC perturbations | None | None |
Soil moisture initialization | Climatology | Climatology |
Snow initialization | ERA-Interim | Met Office Global 4D-VAR |
Unperturbed control forecast? | No | No |
Detailed documentation:
Met Office Global Hybrid 4D-VAR: Clayton et al, 2013
More DA details? CM: CM: Will need to know what is required
Data assimilation method for control analysis: 4D Var (atmosphere) and 3DVAR (ocean/sea-ice)
Horizontal and vertical resolution of perturbations: N/A
Perturbations in +/- pairs: N/A
3.2 Ocean and cryosphere
Re-forecast | Forecast | |
---|---|---|
Ocean initialization | GloSea Ocean Sea-Ice Analysis (GS-OSIA) | Forecast Ocean Assimilation Model (FOAM) |
Ocean IC perturbations | No | No |
Unperturbed control forecast? | No | No |
Detailed documentation:
The GS-OSIA and the FOAM system both use the Nucleus for European Modelling of the Ocean data assimilation system (NEMOVAR). This is a 3d-VAR data assimilation scheme. The GS-OSIA uses different surface forcing (ERA-interim) and observation sets as it is a historical analysis. FOAM uses surface forcing from the Met Office Global NWP model and real-time observations.
The common NEMOVAR system is described in Blockley et al, 2014. Details of the GS-OSIA can be found in MacLachlan et al, 2015.
More ocean data assimilation details?
Source and treatment of SST? (Other data sources - altimetry?)
4. Model uncertainties perturbations:
Model dynamics perturbations | None |
---|---|
Model physics perturbations | Atmosphere Stochastic physics scheme. SKEB2 |
If there is a control forecast, is it perturbed? | No control |
Detailed documentation:
5. Forecast system and hindcasts
Forecast frequency | Daily |
---|---|
Forecast ensemble size | 2 per day |
Hindcast years | 23 (1993-2015) |
Hindcast ensemble size | 28 (4 start dates, 7 per start date) |
On-the-fly or static hindcast set? | on-the-fly |
6. Where to find more information