NOUS41 KWBC 121524
PNSWSH

TECHNICAL IMPLEMENTATION NOTICE 07-21
NATIONAL WEATHER SERVICE HEADQUARTERS WASHINGTON DC
1120 PM EDT THU APR 12 2007

TO:       FAMILY OF SERVICES /FOS/ SUBSCRIBERS...NOAA WEATHER 
          WIRE SERVICE /NWWS/ SUBSCRIBERS...EMERGENCY MANAGERS 
          WEATHER INFORMATION NETWORK /EMWIN/ SUBSCRIBERS...OTHER 
          NATIONAL WEATHER SERVICE /NWS/ CUSTOMERS AND PARTNERS 
          ...NWS EMPLOYEES

FROM:     PAUL HIRSCHBERG
          CHIEF...SCIENCE PLANS BRANCH
          OFFICE OF SCIENCE AND TECHNOLOGY /OST/

SUBJECT:  NCEP GLOBAL FORECAST SYSTEM MODEL UPGRADE: EFFECTIVE   
          MAY 1 2007

EFFECTIVE TUESDAY MAY 1 2007...BEGINNING WITH THE 1200 
COORDINATED UNIVERSAL TIME /UTC/ RUN...THE NATIONAL CENTERS FOR 
ENVIRONMENTAL PREDICTION /NCEP/ WILL UPGRADE THE GLOBAL FORECAST 
SYSTEM /GFS/ TO IMPROVE ITS ACCURACY AND PRODUCTS.

THIS UPGRADE WILL INVOLVE IMPROVEMENTS TO BOTH THE ANALYSIS AND 
FORECAST OF THE GFS.  DETAILS OF THESE CHANGES ARE AS FOLLOWS:

ANALYSIS CHANGES:

1.  REPLACE SPECTRAL STATISTICAL INTERPOLATION /SSI/ ANALYSIS    
    SYSTEM WITH GRIDPOINT STATISTICAL INTERPOLATION /GSI/ 
    ANALYSIS SYSTEM.
      
2.  USE OF INCREASED OBSERVATIONS INCLUDING FULL RESOLUTION    
    ATMOSPHERIC INFRARED SOUNDER /AIRS/ DATA...CONSTELLATION     
    OBSERVING SYSTEM FOR METEOROLOGY...IONOSPHERE AND CLIMATE    
    /COSMIC/ GLOBAL POSITIONING SYSTEM RADIO OCCULTATION /GPSRO/ 
    DATA.

MODEL CHANGES:

3.  MODIFY SIGMA COORDINATE SYSTEM TO A HYBRID SIGMA-PRESSURE
    COORDINATE SYSTEM.
	
4.  UPDATED GFS RADIATION MODULE

PRODUCT CHANGES:

5.  SURFACE FLUX FILES HAVE 30 NEW RECORDS MAINLY FOR            
    HYDROLOGICAL USE

6.  CHANGE OUTPUT OF GLOBAL DIAGNOSTIC ASSIMILATION SYSTEM       
    /GDAS/ FROM 3-HOURLY TO HOURLY

7.  MODEL TO NATIVE OUTPUT FILE WILL CHANGE FROM A SIGMA         
    SPECTRAL BINARY FILE TO A HYBRID SPECTRAL BINARY FILE

PLEASE NOTE THAT THERE WILL BE NO CHANGES TO THE GFS PRODUCTS 
BEING SENT OVER NOAAPORT WITH THIS UPGRADE.

EXPECTED IMPROVEMENTS/CHANGES:

THE GFS FORECAST SHOULD HOLD THE ASIAN JET EAST OF THE HIMALAYAS
BETTER.  THE GFS FORECAST SHOULD BE SLIGHTLY IMPROVED OVERALL IN 
THE STRATOSPHERE.  THE OVERALL TROPICAL SKILL OF THE GFS 
FORECASTS SHOULD IMPROVE.  THE EXTRATROPICAL SKILL SHOULD IMPROVE 
IN THE SHORT LEAD TIMES BUT BE ABOUT THE SAME IN THE MEDIUM 
RANGE.  THE UNIFIED GSI ANALYSIS SYSTEM ENABLES NEW OBSERVATION 
SYSTEMS AND IS MORE ADAPTABLE FOR FUTURE UPGRADES.

RETROSPECTIVE EVALUATION:

THE GFS SYSTEM HAS BEEN RETROSPECTIVELY EVALUATED FOR THE 
FOLLOWING PERIODS:

JULY 1 2005 – OCTOBER 31 2005
SEPTEMBER 1 2006 – OCTOBER 31 2006
NOVEMBER 1 2006 – JANUARY 31 2007

RESULTS FROM THESE RETROSPECTIVE RUNS CAN BE VIEWED AT /USE LOWER 
CASE LETTERS/:

    HTTP://WWWT.EMC.NCEP.NOAA.GOV/GMB/PARA/PARALOG.GSIHYBRID.HTML

NCEP CENTRAL OPERATIONS IS CURRENTLY RUNNING A REAL-TIME PARALLEL 
RUN VERSION OF THE GFS WITH THESE UPGRADES.  RESULTS FROM THESE 
PARALLEL RUNS CAN BE VIEWED AT /USE LOWER CASE LETTERS/:

    HTTP://WWW.NCO.NCEP.NOAA.GOV/PMB/NWPARA/ANALYSIS

THE EFFECTIVE DATE OF THIS CHANGE IS SOONER THAN SPECIFIED BY NWS 
POLICY.  THE SHORTER ADVANCE LEAD TIME WAS CAUSED BY THE 
NECESSITY TO CONDUCT AN EVALUATION OF THE GFS MODEL OUTPUT 
STATISTICS /MOS/ GUIDANCE PRODUCTS. RESULTS OF THE EVALUATION 
CONCLUDED THAT THERE WILL BE LITTLE IF ANY IMPACT ON GFS MOS 
GUIDANCE PRODUCTS.  THE SHORTER LEAD TIME WAS APPROVED BECAUSE IT 
IS EXPECTED THAT USERS WILL NOT HAVE TO MAKE MAJOR ADJUSTMENTS TO 
ACCOMMODATE THESE CHANGES. 

IF YOU HAVE ANY QUESTIONS ABOUT THESE CHANGES...PLEASE CONTACT 

DR. MARK IREDELL  
NCEP...GLOBAL MODELING BRANCH  
CAMP SPRINGS MARYLAND  
PHONE: 301 763 8000 X7231  
EMAIL: MARK.IREDELL@NOAA.GOV  
 
OR  
 
KEN CAMPANA  
NCEP...GLOBAL MODELING BRANCH  
CAMP SPRINGS MARYLAND  
PHONE: 301 763 8000 X7228  
EMAIL: KENNETH.CAMPANA@NOAA.GOV

THIS AND OTHER NWS TECHNICAL IMPLEMENTATION NOTICES ARE AVAILABLE 
ONLINE AT /USE LOWER CASE LETTERS/: 
 
    HTTP://WWW.NWS.NOAA.GOV/OM/NOTIF.HTM 
 
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