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Next Generation Earth System Prediction: Strategies for Subseasonal to Seasonal Forecasts (2016)

Chapter: Appendix B: Details of Seasonal and Subseasonal Forecast Systems

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Suggested Citation:"Appendix B: Details of Seasonal and Subseasonal Forecast Systems." National Academies of Sciences, Engineering, and Medicine. 2016. Next Generation Earth System Prediction: Strategies for Subseasonal to Seasonal Forecasts. Washington, DC: The National Academies Press. doi: 10.17226/21873.
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APPENDIX B

Details of Seasonal and Subseasonal Forecast Systems

EXAMPLES OF MODELS USED BY OPERATIONAL CENTERS FOR SUBSEASONAL AND SEASONAL FORECASTING

At the National Centers for Environmental Prediction (NCEP), the Climate Forecasting System version 2 (CFSv2) is currently used for both the subseasonal and seasonal (S2S) predictions. CFSv2 is a fully coupled model representing the interaction between the Earth’s atmosphere, oceans, land, and sea ice (Saha et al., 2014). It became operational at NCEP in March 2011. The atmospheric model has a horizontal resolution of T126 (about 100 km) and 64 vertical levels. The ocean component is the Modular Ocean Model developed by the Geophysical Fluid Dynamics Laboratory (GFDL) with 0.5 to 0.25 degree resolution and 40 vertical levels, and with an interactive sea ice model. For the subseasonal forecast (defined by NCEP as days 0-45), 16 members are run every day (4 members run four times a day at 00Z, 06Z, 12Z, and 18Z). The retrospective forecasts are done from 1999 to 2010, four members a day. For the seasonal forecast (defined by NCEP as months 0-9), four runs per day are performed. The retrospective forecasts are constructed with four members run every fifth day for the past 29 years (1982-2010).

The European Centre for Medium-Range Weather Forecasting (ECMWF) utilizes two different systems for the S2S predictions. The operational seasonal forecasting system, known as System 4, was implemented in 2011. The atmospheric model is the ECMWF Integrated Forecast System (IFS) model frozen version 36r4. It has a horizontal resolution of TL255 (~60km) and 91 vertical levels. The ocean component is from the Nucleus for European Modeling of the Ocean (NEMO), with the ORCA1 configuration, which has a 1x1 degree resolution in midlatitudes and enhanced meridional resolution near the equator. The retrospective forecast is done from 1981 to 2010 for 15 members for 7 months initialized with ECMWF Interim Reanalysis (ERA Interim) on the first day of each month. The seasonal forecasts consist of a 51-member ensemble. The ensemble is constructed by combining the 5-member ensemble ocean analysis with sea surface temperature (SST) perturbations and the activation of stochastic physics. The forecasts have an initial date of the 1st of each month, and run for 7 months. For

Suggested Citation:"Appendix B: Details of Seasonal and Subseasonal Forecast Systems." National Academies of Sciences, Engineering, and Medicine. 2016. Next Generation Earth System Prediction: Strategies for Subseasonal to Seasonal Forecasts. Washington, DC: The National Academies Press. doi: 10.17226/21873.
×

the subseasonal prediction, ECMWF’s monthly forecasting system is used. The atmospheric model is the same version as ECMWF’s deterministic forecast. The atmospheric model is run at TL639 resolution from day 0 to day 10 and at T319 from day 10 to 32 with 62 vertical levels. The ocean component is also NEMO with the ORCA1 configuration. Fifty-one members run to 46 days twice a week (Monday and Thursday at 00Z). The ocean and atmosphere models are fully coupled, and the retrospective forecasts are constructed with 11 members run at the same day and month as the Thursday real-time forecast over the past 20 years.

Additional details about these and other operational seasonal forecast systems are shown in Table B.1, and Table B.2 provides similar information for subseasonal systems.

Suggested Citation:"Appendix B: Details of Seasonal and Subseasonal Forecast Systems." National Academies of Sciences, Engineering, and Medicine. 2016. Next Generation Earth System Prediction: Strategies for Subseasonal to Seasonal Forecasts. Washington, DC: The National Academies Press. doi: 10.17226/21873.
×

TABLE B.1 Forecast and retrospective forecast system characteristics of the 12 Global Prediction Centers (GPC) of the WMO. SOURCE: Adapted from the S2S Research Implementation Plan and http://www.wmo.int/pages/prog/wcp/wcasp/gpc/gpc.php (accessed January 27, 2016).

Time range Model Resolution Coupled Ensemble Size Frequency Reforecast length Reforecast frequency Reforecast size
BoM m 0-9 POAMA T47L17 yes 33 2/week 1981-2010 6/month 33
CMA m 0-3 BCC-CM1 T63L16 yes 48 1/month 1982-now 1/month 6
EC m 0-12 CanSIPS T63L35 yes 20 1/month 1981-2010 1/month 20
ECMWF m 0-7/12 System4 T255L91 yes 51 1/month 1981-2010 1/month 15
HMCR m 0-4 SL-AV 1.1x1.4L28 no 20 1/month 1981-2010 1/month 10
JMA m 0-3/6 JMA/MRI-CPS2 TL150L60 yes 51 1/month 1979-2010 2/month 5
KMA m 0-3/6 GDAPS T106L21 no 20 1/month 1979-2010 1/month 20
Météo-France m 0-7 ARPEGE T63L31 yes 41 1/month 1993-2003 1/month 5
NCEP m 0-9 CFSv2 T126L64 yes 40 1/month 1982-2010 1/month 24
UKMO m 0-6 GloSea5 N216L85 yes 42 1/week 1996-2009 4/month 12
CPTEC m 0-7 CPTEC AGCM T62L28 no 15 1/month 1979-2001 1/month 10
SAWS m 0-5 ECHAM4.5 T42L19 no 6 1/month 1981-2001 1/month 6
Suggested Citation:"Appendix B: Details of Seasonal and Subseasonal Forecast Systems." National Academies of Sciences, Engineering, and Medicine. 2016. Next Generation Earth System Prediction: Strategies for Subseasonal to Seasonal Forecasts. Washington, DC: The National Academies Press. doi: 10.17226/21873.
×

TABLE B.2 Forecast and retrospective forecast system characteristics for subseasonal forecasting systems from operational centers participating in the WCRP-WWRP Subseasonal to Seasonal Prediction Project. SOURCE: Adapted from s2sprediction.net and https://software.ecmwf.int/wiki/display/S2S/Models, both accessed January 27, 2016.

Time range Resolution Ensemble Size Frequency Reforecasts Reforecast length Reforecast frequency Reforecast size
BoM (ammc) d 0-60 T47L17 33 2/week fix 1981-2013 6/month 33
CMA (babj) d 0-60 T106L40 4 daily fix 1994-2014 daily 4
EC (cwao) d 0-32 0.6x0.6 L40 21 weekly on the fly 1995-2012 weekly 4
ECMWF (ecmf) d 0-46 T639/319 L62 51 2/week on the fly past 20 years 2/week 11
HMCR (rums) d 0-63 1.1x1.4 L28 20 weekly fix 1985-2010 weekly 10
ISAC-CNR (isac) d 0-32 0.75x0.56 L54 40 weekly fix 1981-2010 6/month 1
JMA (rjtd) d 0-34 T319L60 25 2/week fix 1981-2010 3/month 5
KMA (rksl) d 0-60 N216L85 4 daily on the fly 1996-2009 4/month 3
Météo-France (lfpw) d 0-61 T255L91 51 monthly fix 1993-2014 2/monthly 15
NCEP (kwbc) d 0-44 T126L64 16 daily fix 1999-2010 day 4
UKMO (egrr) d 0-60 N216L85 4 daily on the fly 1996-2009 4/month 3
Suggested Citation:"Appendix B: Details of Seasonal and Subseasonal Forecast Systems." National Academies of Sciences, Engineering, and Medicine. 2016. Next Generation Earth System Prediction: Strategies for Subseasonal to Seasonal Forecasts. Washington, DC: The National Academies Press. doi: 10.17226/21873.
×
Page 319
Suggested Citation:"Appendix B: Details of Seasonal and Subseasonal Forecast Systems." National Academies of Sciences, Engineering, and Medicine. 2016. Next Generation Earth System Prediction: Strategies for Subseasonal to Seasonal Forecasts. Washington, DC: The National Academies Press. doi: 10.17226/21873.
×
Page 320
Suggested Citation:"Appendix B: Details of Seasonal and Subseasonal Forecast Systems." National Academies of Sciences, Engineering, and Medicine. 2016. Next Generation Earth System Prediction: Strategies for Subseasonal to Seasonal Forecasts. Washington, DC: The National Academies Press. doi: 10.17226/21873.
×
Page 321
Suggested Citation:"Appendix B: Details of Seasonal and Subseasonal Forecast Systems." National Academies of Sciences, Engineering, and Medicine. 2016. Next Generation Earth System Prediction: Strategies for Subseasonal to Seasonal Forecasts. Washington, DC: The National Academies Press. doi: 10.17226/21873.
×
Page 322
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As the nation’s economic activities, security concerns, and stewardship of natural resources become increasingly complex and globally interrelated, they become ever more sensitive to adverse impacts from weather, climate, and other natural phenomena. For several decades, forecasts with lead times of a few days for weather and other environmental phenomena have yielded valuable information to improve decision-making across all sectors of society. Developing the capability to forecast environmental conditions and disruptive events several weeks and months in advance could dramatically increase the value and benefit of environmental predictions, saving lives, protecting property, increasing economic vitality, protecting the environment, and informing policy choices.

Over the past decade, the ability to forecast weather and climate conditions on subseasonal to seasonal (S2S) timescales, i.e., two to fifty-two weeks in advance, has improved substantially. Although significant progress has been made, much work remains to make S2S predictions skillful enough, as well as optimally tailored and communicated, to enable widespread use. Next Generation Earth System Predictions presents a ten-year U.S. research agenda that increases the nation’s S2S research and modeling capability, advances S2S forecasting, and aids in decision making at medium and extended lead times.

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