http://www.lineameteo.it/viewtopic.php?f=1&t=5985&p=96730#p96730
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andrea75
Lun 29 Dic, 2008 11:18

Re: GFS Cambia
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Ulteriori notizie. Questo il datasheet rilasciato dal sito della NCEP

[cell class=spoiler][tt]NOUS41 KWBC 081222 AAA
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 VARIANCES
7.  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. USER’S 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/PARA

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

NWS TECHNICAL IMPLEMENTATION NOTICES ARE ONLINE AT  
/USE LOWER CASE/:

     HTTP://WWW.NWS.NOAA.GOV/OM/NOTIF.HTM

[/tt][/cell]

Sembrerebbe, stando almeno alla loro presentazione, che questa nuova versione debba diventare definitivamente operativa a Marzo 2009, anche se in effetti da Dicembre in poi saranno mensilmente rilasciate una sorta di versioni "beta" (quelle che usa Meteociel e che il sito stesso renderà operative da Gennaio). 
Nessuna altra modifica di rilievo è prevista per GFS nel 2009, anche perchè è in corso la migrazione su un nuovo sistema di elaborazione.
Ci sarà invece una modifica alle ENS di GFS, sia per quanto riguarda i vari metodi di perturbazione sia per quanto riguarda la risoluzione orizzontale del modello, che scende da 100 a 70 km.
Interpretando le presentazioni di NCEP mi sembra che i loro sforzi per i prossimi anni saranno concentrati su una piattaforma comune ai vari modelli per l'assimilazione dei dati. GFS tirerà a campare mentre i maggiori sviluppi saranno sul modello di previsione degli uragani e CFS.

Qui trovate cmq tutta lista dei vari fix e delle modifiche al modello e ai dati di inizializzazione:

http://www.nco.ncep.noaa.gov/pmb/changes/

Per ora mi fermo qui, ma mi riprometto di indagare ancora meglio. :bye:


