1. Forecast system version
Identifier code: cwao_CanCM4i
First operational forecast run: 31 July 2019
2. Configuration of the forecast model
Is the model coupled to an ocean model? Yes
Coupling frequency: 24 hours
2.1 Atmosphere and land surface
Model | CanAM4 |
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Horizontal resolution and grid | T63 (~2.8 degrees lat/lon) |
Atmosphere vertical resolution | 35 hybrid levels |
Top of atmosphere | 1 hPa |
Soil levels | 3 (0-10 cm; 10-35 cm; 35-410 cm maximum depth) |
Time step | 15 minutes |
Detailed documentation:
von Salzen, K., and Coauthors, 2013: The Canadian fourth generation atmospheric global climate model (CanAM4). Part I: Representation of physical processes. Atmos. -Ocean, 51, 104–125, https://doi.org/10.1080/07055900.2012.755610
2.2 Ocean and cryosphere
Ocean model | CanOM4 |
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Horizontal resolution | ~1.4 degrees (lon), ~0.94 degrees (lat) |
Vertical resolution | 40 levels with ~10m spacing near surface |
Time step | 20 minutes |
Sea ice model | CanICE |
Sea ice model resolution | ~2.8 degrees lat/lon |
Sea ice model levels | 1 |
Wave model | N/A |
Wave model resolution | N/A |
Detailed documentation:
Merryfield, W. J., and Coauthors, 2013: The Canadian seasonal to interannual prediction system. Part I: Models and initialization. Mon. Wea. Rev., 141, 2910–2945, https://doi.org/10.1175/MWR-D-12-00216.1
3. Initialization and initial condition (IC) perturbations
3.1 Atmosphere and land
Hindcast | Forecast | |
---|---|---|
Atmosphere initialization | ERA-Interim | ECCC GDPS analysis |
Atmosphere IC perturbations | Ensemble of coupled assimilation runs begun from different initial conditions. | Ensemble of coupled assimilation runs begun from different initial conditions. |
Land Initialization | Land component forced by assimilating atmosphere. | Land component forced by assimilating atmosphere. |
Land IC perturbations | Each ensemble member forced by slightly different atmospheric states constrained by ERA-Interim | Each ensemble member forced by slightly different atmospheric states constrained by GDPS analysis |
Soil moisture initialization | Soil moisture forced by assimilating atmosphere. | Soil moisture forced by assimilating atmosphere. |
Snow initialization | Snow forced by assimilating atmosphere. | Snow forced by assimilating atmosphere. |
Unperturbed control forecast? | No (all ensemble members contain statistically equivalent perturbations). | No (all ensemble members contain statistically equivalent perturbations). |
Data assimilation method for control analysis:
Incremental Analysis Update (IAU) constrained by (re)analysis 6-hourly temperature, specific humidity and horizontal wind components, modified by inserting only 1/4 of increment on spatial scales >~1000 km.
Horizontal and vertical resolution of perturbations:
Perturbations are primarily on spatial scales <1000 km, vertical structure not directly specified.
Perturbations in +/- pairs:
No, all perturbations represent random samples from a distribution.
Detailed documentation:
Merryfield, W. J., and Coauthors, 2013: The Canadian seasonal to interannual prediction system. Part I: Models and initialization. Mon. Wea. Rev., 141, 2910–2945, https://doi.org/10.1175/MWR-D-12-00216.1
Sospedra-Alfonso, R., L. Mudryk, W. J. Merryfield, and C. Derksen, 2016: Representation of snow in the Canadian Seasonal to Interannual Prediction System: Part I. Initialization.J. Hydrometeor., 17, 1467–1488, https://doi.org/10.1175/JHM-D-14-0223.1
3.2 Ocean and cryosphere
Hindcast | Forecast | |
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Ocean initialization |
|
|
Ocean IC perturbations | Perturbations due to forcing of ocean surface by different realizations of assimilating atmosphere in coupled runs. | Perturbations due to forcing of ocean surface by different realizations of assimilating atmosphere in coupled runs. |
Unperturbed control forecast? | No | No |
Detailed documentation:
Dirkson, A., W. J. Merryfield, and A. Monahan, 2017: Impacts of sea ice thickness initialization on seasonal Arctic sea ice predictions. J. Climate, 30, 1001–1017, https://doi.org/10.1175/JCLI-D-16-0437.1
Merryfield, W. J., and Coauthors, 2013: The Canadian seasonal to interannual prediction system. Part I: Models and initialization. Mon. Wea. Rev., 141, 2910–2945, https://doi.org/10.1175/MWR-D-12-00216.1
Lin, H., Merryfield, W. J., Muncaster, R., Smith, G. C., Markovic, M., Dupont, F., Roy, F., Lemieux, J.-F., Dirkson, A., Kharin, V. V., and Lee, W. S., 2020: The Canadian Seasonal to Interannual Prediction System Version 2 (CanSIPSv2), Weather and Forecasting, 35, 1317–1343, https://doi.org/10.1175/WAF-D-19-0259.1
4. Model Uncertainties perturbations:
Model dynamics perturbations | No |
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Model physics perturbations | No |
If there is a control forecast, is it perturbed? | No control forecast |
Detailed documentation:
5. Forecast system and hindcasts
Forecast frequency | 12-month forecast is produced once per month. (Hindcasts are initialized on the first day of each month, forecasts on the last day of previous month. |
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Forecast ensemble size | 10 |
Hindcast years | All years since 1980 |
Hindcast ensemble size | 10 |
On-the-fly or static hindcast set? | static |
Calibration (bias correction) period | 1981-2010, transitioning to 1991-2020 in late 2020 |