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Published byEdwina MargaretMargaret Barnett Modified over 9 years ago
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1 Global Ensemble Strategy Presented By: Yuejian Zhu (NWS/NCEP) Contributors: EMC staff
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2 Operational System Attribute(s) System NameAcronymAreal Coverage Horz Res Cycle Freq Fcst Length (hr) Global Ensemble Forecast SystemGEFSGlobal34km/ 52km 6hrs384hrs North American Ensemble Forecast System (NCEP+CMC) NAEFSGlobal50km12hrs384hrs National Unified Operational Prediction Capability (NCEP+CMC+FNMOC) NUOPCGlobal50km12hrs384hrs SystemAttributes GEFSDA:NCEP hybrid GSI/EnKF; Ini: EnKF (f06) + TS relocation + Centered all perturbed vectors; Model: GFS NAEFS (CMC)DA: 4DV; Ini: EnKF; Model: GEM – gridded model NUOPC (FNMOC)DA: 4DV; Ini: Banded ET; Model: NAVGEM – spectrum model System Data Assimilation or Initialization Technique
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3 Why System(s) are Operational? Primary stakeholders and requirement drivers All NCEP service centers; NWS WFO/RFC; MDL and NWC Public and private user/sector NAEFS – MOU of US, Canada and Mexico NUOPC – MOU of NOAA and DoD (?) What products are the models contributing to? Global products (300+ variables) at 0.5degree resolution Every 3hrs/6hrs out to 8/16 days Key products: PQPF, T2m, Wind@10m, Hurricane tracks What product aspects are you trying to improve with your development plans? PQPF, T2m, Wind@10m (especially for CONUS and OCONUS) Hurricane track and intensity Top 3 System Performance Strengths Ensemble mean - 500hPa height; hurricane track; T2m Probabilistic guidance – PQPF, forecast uncertainty (RMOP) Extreme weather events Top 3 System Performance Challenges Improvement of sensible weather elements Reduce model bias Extended-range hurricane track forecasts (beyond day 5)
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4 System Evolution Over the Next 5 Years Major forcing factors User requirement and seamless forecast approach Key component of WRN (weather ready nation) Science and development priorities Represent initial (or analysis) uncertainty Near surface, land and ocean Represent model (dynamical and/or physical) uncertainty Stochastic parameterizations Add value through multi-model ensemble approach (NAEFS and NUOPC) What are your top challenges to evolving the system(s) to meet stakeholder requirements? Resources and trade-off Tasks: seamless forecast - both of short-range and week-2 Upgrade: frequently (from WPC …) and less frequently ( from NWC …) Potential opportunities for simplification going forward NGGPS? Unified coupled global model
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5 Top 3 Things You Need From the UMAC 1.Like to understand a key difference of NCEP and ECMWF global (ensemble) system development? Strategy of science and technique; Or management and user requirement; Or resource? 2.Is it important to have coupling system for short-term (or weather) forecast when we face many challenges today? If not, what our priority should be? 3.A challenge to have one global ensemble system to cover 1-30 days (short-term and extended-range) forecast. Uniform or variable resolutions? Ensemble size?
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6 Extra slides for reference
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7 NCEPCMCNAEFS ModelGFSGEMNCEP+CMC Initial uncertaintyETRETKFETR + ETKF Model uncertainty/Stochasti c Yes (Stochastic Pert)Yes (multi-physics and stochastic) Yes Tropical stormRelocationNone Daily frequency00,06,12 and 18UTC00 and 12UTC ResolutionT254L42 (d0-d8)~55km T190L42 (d8-16)~70km About 50km L72 1*1 degree ControlYes Yes (2) Ensemble members20 for each cycle 40 for each cycle Forecast length16 days (384 hours) 16 days Post-processBias correction (same bias for all members) Bias correction for each member Yes Last implementationFebruary 14 th 2012November 18 th 2014 NAEFS Current Status Updated: November 18 th 2014
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NCEPCMCFNMOC ModelGFSGEMGlobal Spectrum Initial uncertaintyETREnKF(9) Banded ET Model uncertainty Stochastic Yes (STTP)Yes (multi-physics and Stochastic) None Tropical stormRelocationNone Daily frequency00,06,12 and 18UTC00 and 12UTC ResolutionT254L42 (d0-d8)~55km T190L42 (d8-16)~70km ~ 50km L72 T239L50 ~ 55km ControlYes Ensemble members20 for each cycle Forecast length16 days (384 hours) Post-processBias correction for ensemble mean Bias correction for each member Bias correction for member mean Last implementationFebruary 14 2012November 18 2014May 21 2014 NUOPC Current Status Updated: November 18 th 2014
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