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1. Forecast system version
System name: GloSea6-GC3.2
First operational forecast run: 2 Feb 2021
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 3.2 (GC3.2) is described in Williams et al, 20192018.
2.1 Atmosphere and land surface
Model | Met Office Unified Model (UM) - Global Atmosphere 7.2 Joint UK Land Environment Simulator (JULES) - Global Land 8.0 |
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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 (layers) | 4 |
Layer 1 : 0 - 0.1 m |
Layer 2 : 0.1 - 0.35 |
Layer 3 : 0.35 - 1.0 m |
Layer 4 : 1.0 - 3.0 m | |
Time step | 15 minutes |
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Detailed documentation:
Global Atmosphere 7.0/7.1 & Global Land 7.0: Walters et al, 2017
2.2 Ocean and cryosphere
Ocean model | NEMO v3.6 - Global Ocean 6.0 |
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Horizontal resolution | ORCA 0.25 |
Vertical resolution | L75 |
Time step | 20 minutes |
Sea ice model | CICE v5.1.2 - Global Sea-Ice 8.1 |
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 8.0: Ridley et al, 2017
3. Initialization and initial condition (IC) perturbations
3.1 Atmosphere and land
Hindcast | Forecast | |
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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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JRA55 analysis: Kobayashi et al. 2015, Kobayashi Harada et al. 2016
3.2 Ocean and cryosphere
Hindcast | Forecast | |
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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 |
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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 |
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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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