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Table of Contents
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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

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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
Land vertical resolution15 layers (see table below)
Top of atmosphere0.2 hPa (60 km approx.)
Soil layers15 layers: 10 soil layers plus 5 bedrock layers (for layer depths, see table below)
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).

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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 vertical levels
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

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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 (obs. atmosphere) monthly run

initialized from 10-year spin-up

Forced (obs. atmosphere) monthly run

initialized from 10-year spin-up

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

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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?NONO

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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

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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 ICs, the 3 land perturbed ICs and the 8 (4 in hindcast mode) are combined to yield 240 (120 in hindcast mode) possible perturbed ICs among which the 50 ICs (40 in hindcast mode) to produce the forecast ensemble are chosen at random.

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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

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