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-------- Original Message --------213 NOUS41 KWBC 081222
PNSWSH
TECHNICAL IMPLEMENTATION NOTICE 08-31 AMENDED
NATIONAL WEATHER SERVICE HEADQUARTERS WASHINGTON DC
822 AM EDT THU MAY 8 2008
TO: SUBSCRIBERS:
-FAMILY OF SERVICES
-NOAA WEATHER WIRE SERVICE
-EMERGENCY MANAGERS WEATHER INFORMATION NETWORK
OTHER NWS PARTNERS...USERS AND EMPLOYEES
FROM: JASON TUELL
SCIENCE PLANS BRANCH CHIEF
OFFICE OF SCIENCE AND TECHNOLOGY
SUBJECT: AMENDED: GLOBAL FORECAST SYSTEM CHANGES:
EFFECTIVE DATE CHANGED TO JUNE 3 2008
REFER TO: TECHNICAL IMPLEMENTATION NOTICE /TIN/ 08-31
TRANSMITTED ON APRIL 2 2008
AMENDED TO DELAY THE IMPLEMENTATION DATE FROM MAY 13 2008 TO JUNE 3 2008 TO ALLOW FOR ADDITIONAL TESTING. FURTHER DELAY IS POSSIBLE DEPENDING ON TEST RESULTS. ANOTHER AMENDMENT WILL BE ISSUED IF THERE IS NECESSARY. THE ORIGINAL NOTICE...WITH A REVISED DATE...IS GIVEN BELOW: EFFECTIVE JUNE 3 2008...BEGINNING WITH THE 1200 COORDINATED UNIVERSAL TIME /UTC/ RUN...SEVERAL CHANGES WILL BE MADE TO THE GLOBAL FORECAST SYSTEM /GFS/ MODELING SYSTEM. THESE CHANGES ARE BEING MADE TO IMPROVE MODEL PERFORMANCE.
THE FOLLOWING FOUR CHANGES INVOLVE A SIGNIFICANT UPGRADE IN THE CONSISTENCY AND ACCURACY OF THE MODEL RADIATION PARAMETERIZATIONS:
1. HOURLY RRTM1 LONGWAVE RADIATION RRTM SHORTWAVE RADIATION 2. MAXIMUM-RANDOM CLOUD OVERLAP FOR SHORTWAVE GENERALIZED AEROSOL TREATMENT AND REALISTIC CO2 3. MINOR ADJUSTMENTS OF OROGRAPHIC GRAVITY WAVE VARIANCE RANGE LIMITS AND MOUNTAIN BLOCKING BUG FIX 4. ENTHALPY THERMODYNAMIC PROGNOSTIC VARIABLE WHICH ALLOWS FOR GREATER FLEXIBILITY AND IN CARRYING ATMOSPHERIC CONSTITUENTS
THE ANALYSIS CHANGES INCLUDE: 1. ADDING WINDSAT NEAR SURFACE WINDS 2. ADDING NOAA-18 SBUV/2 OZONE 3. FOTO /FIRST-ORDER TIME-EXTRAPOLATION TO OBSERVATIONS/ 4. VARIATIONAL QC 5. CHANGE IN LAND/SNOW/ICE SKIN TEMPERATURE VARIANCE 6. FLOW DEPENDENT RE-WEIGHTING OF BACKGROUND ERROR VARIANCES7. BUG FIXES TO PROCESSING OF COSMIC GPSRO DATA...GROSS CHECK...AND ADJUSTMENT OF OBSERVATION ERROR FOR VERTICALLY DENSE OBSERVATIONS
8. CODE AND SCRIPT OPTIMIZATION OTHER OUTPUT CHANGES INCLUDE:1. THE INTERNAL MODEL SPECTRAL /SIGMA/ FILE IS CHANGING ITS FORMAT SLIGHTLY. THIS FILE IS NOT USED FOR PRODUCTS. ONLY ITS HEADER INFORMATION IS CHANGING. USERS GUIDE AND SAMPLE CODE AND FILES CAN BE FOUND AT /USE LOWER CASE LETTERS/:
HTTP://WWW.EMC.NCEP.NOAA.GOV/GMB/IREDELL/GFS/SAMPLE2008/2. THERE ARE NO OTHER OUTPUT CHANGES. NOTABLY NO GRIB PRODUCTS ARE CHANGING.
THE COMBINED IMPACT OF THESE CHANGES HAS LED TO THE FOLLOWING IMPROVEMENTS IN MODEL PERFORMANCE:
1. IMPROVED SKILL IN EXTRATROPICAL 3-DAY FORECAST PERFORMANCE AT 500 MB...PARTICULARLY IN THE SOUTHERN HEMISPHERE BETTER LOWER STRATOSPHERIC THERMODYNAMIC STRUCTURE
2. MORE DETAILS ABOUT THESE CHANGES CAN BE SEEN AT /USE LOWERCASE/:
HTTP://WWW.EMC.NCEP.NOAA.GOV/GMB/WX24FY/VSDB_EXP/SUMMER07/DATA DELIVERY TIMING WILL NOT BE IMPACTED BY THIS IMPLEMENTATION. DATA VOLUMES ARE NOT EXPECTED TO INCREASE. SIGNIFICANT DATA CONTENT CHANGES ARE NOT EXPECTED. THESE MODEL CHANGES WILL IMPACT ALL DISSEMINATION ROUTES WHICH INCLUDE NOAAPORT...THE NWS PUBLIC FTP SERVER AND THE NCEP PUBLIC FTP SERVER. A CONSISTENT PARALLEL FEED OF DATA WILL BECOME AVAILABLE ON THE NCEP FTP SERVER ON APRIL 1 2008 AT THE FOLLOWING URL /USE LOWERCASE/:
FTP://FTP.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PARANCEP WOULD ENCOURAGE ALL USERS TO ENSURE THEIR DECODERS ARE FLEXIBLE AND ARE ABLE TO ADEQUATELY HANDLE CHANGES IN CONTENT ORDER...PARAMETER FIELDS CHANGING ORDER...CHANGES IN THE SCALING FACTOR COMPONENT WITHIN THE PDS OF THE GRIB FILES AND ANY VOLUME CHANGES THAT MAY BE FORTHCOMING. THESE ELEMENTS MAY CHANGE WITH FUTURE NCEP MODEL IMPLEMENTATIONS. NCEP WILL MAKE EVERY ATTEMPT TO ALERT USERS TO THESE CHANGES BEFORE IMPLEMENTATIONS.
FOR QUESTIONS CONCERNING THESE CHANGES...PLEASE CONTACT:
MARK IREDELL NCEP GLOBAL MODELING BRANCH CAMP SPRINGS MARYLAND PHONE: 301-763-8000 X7231 EMAIL: MARK.IREDELL@xxxxxxxx OR KEN CAMPANA NCEP GLOBAL MODELING BRANCH CAMP SPRINGS MARYLAND PHONE: 301-763-8000 X7228 EMAIL: KENNETH.CAMPANA@xxxxxxxxNWS TECHNICAL IMPLEMENTATION NOTICES ARE ONLINE AT /USE LOWER CASE/:
HTTP://WWW.NWS.NOAA.GOV/OM/NOTIF.HTM
$$
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