NCEP Global Ensemble Forecast System (GEFS) Yuejian Zhu Ensemble Team Leader Environmental Modeling Center NCEP/NWS/NOAA February

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1 NCEP Global Ensemble Forecast System (GEFS) Yuejian Zhu Ensemble Team Leader Environmental Modeling Center NCEP/NWS/NOAA February

2 Current Status (since Feb 2012) Model GFS V9.01 (Spectrum, Euler model) implemented by May 2011 Horizontal resolution T254 (52 55km for hours), T190 (70 74km for hours) Vertical resolution 42 hybrid levels Model top: 2hPa Initialization Breeding Vector (BV) and Ensemble Transform with Rescaling (ETR) cycling every 6 hours (80 vectors in cycling) Tropical Storm Relocation (TSR) since 2005 Stochastic perturbation Stochastic Total Tendency Perturbation (STTP) since 2010 Ensemble size and forecast length 20 perturbations plus control 4 cycles per day Out to 16 days Output Every 6 hr for 1*1 degree pressure GRIB format files Full variables for TIGGE data exchange

3 Next Implementation (Q1FY15) Model GFS V10.0 (Spectrum, Semi Lagrangian model) Plan for Q4FY14 Horizontal resolution T574 (T382 physics: 33 35km for hours), T382 (T254 physics: 52 55km for hours) Vertical resolution 64 hybrid levels to match GSI/EnKF hybrid analysis system Model top: 0.2hPa Initialization Hybrid EnKF f06 and Ensemble Transform with Rescaling (ETR 3 dimension) Improved Tropical Storm Relocation (TSR) scheme Stochastic perturbation Stochastic Total Tendency Perturbation (STTP) Ensemble size and forecast length 20 perturbations plus control 4 cycles per day Out to 16 days Output and data exchange Every 3 hr for 0.5*0.5 degree pressure GRIB format files Full variables for TIGGE data exchange (1*1 degree, every 6 hr)

4 Future Plan (end of FY18) Model GFS V11.0 (Spectrum, Semi Lagrangian model) Plan for FY16(?) Horizontal resolution 0 168hrs 15 17km hrs 33 35km hrs 52 55km Vertical resolution 64 hybrid levels Model top: 0.2hPa Initialization Hybrid EnKF and ETR Advanced Tropical Storm Relocation (ATSR) Stochastic perturbation Stochastic Total Tendency Perturbation (STTP) Various stochastic physical perturbations Surface perturbation and coupling One/two way(s) coupling with ocean model Perturbed land surface model Ensemble size and forecast length 20 (?) perturbations plus control 4 cycles per day Out to 30 days Real time reforecast Past 20 years Once per week (at least)

5 Additional Information

6 North American Ensemble Forecast System (NAEFS) International project to produce operational multicenter ensemble products Bias correction and combines global ensemble forecasts from Canada & USA Generates products for: Weather forecasters Specialized users End users Operational outlet for THORPEX research using TIGGE archive

7 Statement The North American Ensemble Forecast System (NAEFS) combines state of the art weather forecast tools, called ensemble forecasts, developed at the US National Weather Service (NWS) and the Meteorological Service of Canada (MSC). When combined, these tools (a) provide weather forecast guidance for the 1 14 day period that is of higher quality than the currently available operational guidance based on either of the two sets of tools separately; and (b) make a set of forecasts that are seamless across the national boundaries over North America, between Mexico and the US, and between the US and Canada. As a first step in the development of the NAEFS system, the two ensemble generating centers, the National Centers for Environmental Prediction (NCEP) of NWS and the Canadian Meteorological Center (CMC) of MSC started exchanging their ensemble forecast data on the operational basis in September First NAEFS probabilistic products have been implemented at NCEP in February The enhanced weather forecast products are generated based on the joint ensemble which has been undergone a statistical post processing to reduce their systematic errors.

8 NAEFS Milestones Implementations First NAEFS implementation bias correction IOC, May Version 1 NAEFS follow up implementation CONUS downscaling December Version 2 Alaska implementation Alaska downscaling December Version 3 Implementation for CONUS/Alaska expansion Q2FY14 Version 4 Applications of NAEFS Statistical Post Processing: NCEP/GEFS and NAEFS at NWS CMC/GEFS and NAEFS at MSC FNMOC/GEFS at NAVY NCEP/SREF at NWS Publications (or references): Cui, B., Z. Toth, Y. Zhu, and D. Hou, D. Unger, and S. Beauregard, 2004: The Trade off in Bias Correction between Using the Latest Analysis/Modeling System with a Short, versus an Older System with a Long Archive The First THORPEX International Science Symposium. December 6 10, 2004, Montréal, Canada, World Meteorological Organization, P Zhu, Y., and B. Cui, 2006: GFS bias correction [Document is available online] Zhu, Y., B. Cui, and Z. Toth, 2007: December 2007 upgrade of the NCEP Global Ensemble Forecast System (NAEFS) [Document is available online] Cui, B., Z. Toth, Y. Zhu and D. Hou, 2012: "Bias Correction For Global Ensemble Forecast" Weather and Forecasting, Vol Cui, B., Y. Zhu, Z. Toth and D. Hou, 2013: "Development of Statistical Post processor for NAEFS Weather and Forecasting (In process) Zhu, Y., and B. Cui, 2007: December 2007 upgrade of the NCEP Global Ensemble Forecast System (NAEFS) [Document is available online] Zhu, Y, and Y. Luo, 2013: Precipitation Calibration Based on Frequency Matching Method (FMM). Weather and Forecasting (in process) Glahn, B., 2013: A Comparison of Two Methods of Bias Correcting MOS Temperature and Dewpoint Forecasts MDL office note, 13 1

9 NAEFS Current Status Updated: February NCEP CMC NAEFS Model GFS GEM NCEP+CMC Initial uncertainty ETR EnKF ETR + EnKF Model uncertainty/stochastic Yes (Stochastic Pert) Yes (multi-physics and stochastic) Yes Tropical storm Relocation None Daily frequency 00,06,12 and 18UTC 00 and 12UTC 00 and 12UTC Resolution T254L42 (d0-d8)~55km 600*300 (66km) 1*1 degree T190L42 (d8-16)~70km L72 Control Yes Yes Yes (2) Ensemble members 20 for each cycle 20 for each cycle 40 for each cycle Forecast length 16 days (384 hours) 16 days (384 hours) 16 days Post-process Bias correction Bias correction Yes (same bias for all members) for each member Last implementation February 14 th 2012 February

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11 NUOPC National Unified Operational Prediction Capability NUOPC (National Unified Operational Prediction Capability) is an agreement to coordinate activities between the Department of Commerce (National Oceanic and Atmospheric Administration) and the Department of Defense (Oceanographer and Navigator of the Navy and Air Force Directorate of Weather), in order to accelerate the transition of new technology, eliminate unnecessary duplication, and achieve a superior National global prediction capability. The NUOPC partners determined that the Nation s global atmospheric modeling capability can be advanced more effectively and efficiently with their mutual cooperation to provide a common infrastructure to perform and support their individual missions. The NUOPC Tri Agency (NOAA, Navy, Air Force) agreed to work on a collaborative vision through coordinated research, transition and operations in order to develop and implement the nextgeneration National Operational Global Ensemble modeling system. 11

12 NUOPC Current Status Updated: February NCEP CMC FNMOC Model GFS GEM Global Spectrum Initial uncertainty ETR EnKF (9) Banded ET Model uncertainty Stochastic Yes (STTP) Yes (multi-physics and Stochastic) None Tropical storm Relocation None None Daily frequency 00,06,12 and 18UTC 00 and 12UTC 00 and 12UTC Resolution T254L42 (d0-d8)~55km 600*300 (66km) T159L42 ~ 80km T190L42 (d8-16)~70km L72 Control Yes Yes No Ensemble members 20 for each cycle 20 for each cycle 20 for each cycle Forecast length 16 days (384 hours) 16 days (384 hours) 16 days (384 hours) Post-process Bias correction for ensemble mean Bias correction for each member Bias correction for member mean Last implementation February February NAVGEM implementation on February

13 10 day forecast AC score CRPS Northern Hemisphere 500hPa height: 30 day running mean scores of day 10 CRPS skill score RMS error and ratio of RMS error / spread Anomaly correlation RMS error All other regions could be seen from: efs/vrfy_stats/t30_p500hgt