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1. Forecast system version
System name: GloSea5-GC2-LI
First operational forecast run: 2 April 2019
2. Configuration of the forecast model
Is it a coupled model? Yes: Atmosphere, land, ocean and sea-ice.
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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 |
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Global Atmosphere 6.0 & Global Land 6.0: Walters et al, 2017
2.2 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 |
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Global Sea Ice 6.0: Rae et al, 2015.
3. Initialization and initial condition (IC) perturbations
3.1 Atmosphere and land
| Hindcast | Forecast | |
|---|---|---|
| Atmosphere initialization | ERA-Interim | Met Office Global Hybrid 4D-VAR |
| Atmosphere IC perturbations | None | None |
| Soil moisture & temperature initialization | Met Office JULES-JRA55 analysis | Met Office JULES-JRA55 analysis |
| Snow initialization | Met Office JULES-JRA55 analysis | Met Office JULES-JRA55 analysis |
| Unperturbed control forecast? | No | No |
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Met Office Global Hybrid 4D-VAR: Clayton et al, 2013
3.2 Ocean and cryosphere
| Hindcast | 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 |
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The common NEMOVAR system is described in Blockley et al, 2014. Details of the GS-OSIA can be found in MacLachlan et al, 2015.
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 |
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5. Forecast system and hindcasts
| Forecast frequency | daily |
|---|---|
| Forecast ensemble size | 2 per day |
| Hindcast years | 24 (1993-2016) |
| Hindcast ensemble size | 7 per start date |
| Hindcast start dates | 1, 9, 17, 25 of each month |
| On-the-fly or static hindcast set? | on-the-fly |
6. Where to find more information
GloSea5 system:
- MacLachlan, C., Arribas, A., Peterson, K. A., Maidens, A., Fereday, D., Scaife, A. A., Gordon, M., Vellinga, M., Williams, A., Comer, R. E., Camp, J., Xavier, P. and Madec, G. (2015), Global Seasonal forecast system version 5 (GloSea5): a high-resolution seasonal forecast system. Q.J.R. Meteorol. Soc., 141: 1072–1084. doi:10.1002/qj.2396
- Seasonal prediction at the Met Office
- Upgrades to the Met Office Seasonal Forecast System
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