1. Forecast system version

System name: CMCC-SPS3.5

First operational forecast run: 1st October, 2020

2. Configuration of the forecast model

Is it a coupled modelYES

Coupling frequency: 
Atmosphere-Ocean: 90 minutes (every third full time-step of atmospheric model)

Atmosphere-Land: 30 minutes (also full time-step of atmospheric model)

Atmosphere-Sea Ice: 30 minutes (also full time-step of atmospheric model)

Detailed documentation:

CMCC technical documentation Gualdi et al (2020) CMCC Technical Note RP0288 DOI: https://doi.org/10.25424/CMCC/SPS3.5  

2.1 Atmosphere and land surface

Model

CESM 1.2 - CAM 5.3 (Atmosphere)

CESM 1.2 - CLM 4.5 (Land surface)

Horizontal resolution and grid1/2° lat-lon approx
Atmosphere vertical resolution46 levels in the vertical
Top of atmosphere0.2 hPa (60 km approx.)
Soil levels (layers)

15
(10 soil layers plus 5 bedrock layers)

Layer 1 (soil): 0-0.0175m
Layer 2 (soil): 0.0175-0.0451m
Layer 3 (soil): 0.0451-0.0906m
Layer 4 (soil): 0.0906-0.1655m
Layer 5 (soil): 0.1655-0.2891m
Layer 6 (soil): 0.2891-0.4929m
Layer 7 (soil): 0.4929-0,8289m
Layer 8 (soil): 0.8289-1.3828m
Layer 9 (soil): 1.3828-2.2961m
Layer 10 (soil): 2.2961-3.8019m

Time step

Main (Physics) Time-step: 30 minutes.

“Tracer” Advection Time step: 225 seconds
(1/8 of the Physics time step)

Fluid-Dynamics Time step: 56.25 seconds
(1/32 of the Physics time step).

Detailed documentation:

CAM Model documentation http://www.cesm.ucar.edu/models/cesm1.2/cam/

CLM Model documentation http://www.cesm.ucar.edu/models/cesm1.2/clm/

CMCC technical documentation Gualdi et al (2020) CMCC Technical Note RP0288 DOI: https://doi.org/10.25424/CMCC/SPS3.5 

2.2 Ocean and cryosphere

Ocean model

NEMO v3.4

Horizontal resolution1/4°
Vertical resolution50 levels in the vertical
Time step18 minutes
Sea ice modelCICE 4.0
Sea ice model resolution1/4°
Sea ice model levels1 thickness only
Wave modelNO
Wave model resolutionN/A

Detailed documentation:

Nemo Model documentation https://www.nemo-ocean.eu/doc/

CMCC technical documentation Gualdi et al (2020) CMCC Technical Note RP0288 DOI: https://doi.org/10.25424/CMCC/SPS3.5 

3. Initialization and initial condition (IC) perturbations

3.1 Atmosphere and land


HindcastForecast
Atmosphere initialization
ERA5ECMWF IFS operational analysis
Atmosphere IC perturbations1010

Land Initialization

Forced monthly run from a continuous transient simulation with initial-date January 1993, started after a 10 year spinup (with climatological forcings)

Forced monthly run from a continuous transient simulation with initial-date January 1993, started after a 10 year spinup (with climatological forcings)

Land IC perturbations33
Soil moisture initializationFrom land initializationFrom land initialization
Snow initializationFrom land initializationFrom land initialization
Unperturbed control forecast?NONO
Horizontal resolution of perturbationN/AN/A
Perturbations in +/- pairsNONO
Data assimilation method for control analysisERA5ECMWF operational

Detailed documentation:

For more details on atmospheric DA, see ECMWF operational analysis documentation at: https://www.ecmwf.int/en/elibrary/16666-part-ii-data-assimilation 

For more details on ERA5: https://doi.org/10.1002/qj.3803.

CMCC technical documentation Gualdi et al (2020) CMCC Technical Note RP0288 DOI: https://doi.org/10.25424/CMCC/SPS3.5 

3.2 Ocean and cryosphere


HindcastForecast
Ocean initializationC-GLORS
Global Ocean 3D-VAR
C-GLORS
Global Ocean 3D-VAR
Ocean IC perturbations48
Unperturbed control forecast?NOYES

Detailed documentation:

More details on ocean data assimilation at  http://c-glors.cmcc.it/index/index.html

CMCC technical documentation Gualdi et al (2020) CMCC Technical Note RP0288 DOI: https://doi.org/10.25424/CMCC/SPS3.5 

4. Model uncertainties perturbations:

Model dynamics perturbations

NO

Model physics perturbationsYES (Ocean Model only, only during perturbed data assimilation cycles)

If there is a control forecast, is it perturbed?

There is no control forecast

Detailed documentation: For more info on ocean DA perturbations, see Brankart (2013)  DOI: https://doi.org/10.1016/j.ocemod.2013.02.004

CMCC technical documentation Gualdi et al (2020) CMCC Technical Note RP0288 DOI: https://doi.org/10.25424/CMCC/SPS3.5 

5. Forecast system and hindcasts


Forecast frequencyMonthly
Forecast ensemble size50
Hindcast years1993-2016
Hindcast ensemble size40
On-the-fly or static hindcast set?static

6. Other relevant information

The 10 atmospheric perturbed initial conditions, the 3 land perturbed initial conditions and the 9 ocean initial conditions (8 perturbed plus the unperturbed, only 4 perturbed in hindcast mode) are combined to yield 270 (120 in hindcast mode) possible perturbed forecast system initial conditions from which 50 initial conditions (40 in hindcast mode) are chosen at random, to produce the Forecast Ensemble.

Detailed documentation:

CMCC technical documentation Gualdi et al (2020) CMCC Technical Note RP0288 DOI: https://doi.org/10.25424/CMCC/SPS3.5 

7. Where to find more information

Sanna, A., A. Borrelli, P. Athanasiadis, S. Materia, A. Storto, S. Tibaldi, S. Gualdi, 2017: CMCC-SPS3: The CMCC Seasonal Prediction System 3. Centro Euro-Mediterraneo sui Cambiamenti Climatici. CMCC Tech. Note RP0285, 61pp. https://www.cmcc.it/publications/rp0285-cmcc-sps3-the-cmcc-seasonal-prediction-system-3

Gualdi, S., A. Sanna, A. Borrelli, A. Cantelli, M. del Mar Chaves Montero, S. Tibaldi, 2020: The new CMCC Operational Seasonal Prediction System SPS3.5. Centro Euro-Mediterraneo sui Cambiamenti Climatici. CMCC Tech. Note RP0288, 26pp. DOI: https://doi.org/10.25424/CMCC/SPS3.5