NOUS41 KWBC 021255
PNSWSH
  
Technical Implementation Notice 11-07
National Weather Service Headquarters Washington DC
755 AM EST Wed Mar 2 2011
  
To:         Subscribers:
            -Family of Services 
            -NOAA Weather Wire Service
            -Emergency Managers Weather Information Network
            -NOAAPORT 
            Other NWS Partners, Users and Employees
  
From:       Timothy McClung
            Science Plans Branch Chief
            Office of Science and Technology 
 
Subject:    Global Forecast System (GFS) Upgrade:
            Effective April 26, 2011
 
Effective April 26, 2011, beginning with the 1200 Coordinated 
Universal Time (UTC) run, the National Centers for Environmental 
Prediction (NCEP) will upgrade the Global Forecast System (GFS). 
The upgrade includes:
 
Analysis Changes:
  --Improve Ozone Monitoring Instrument (OMI) quality control 
  --Remove redundant SBUV/2 total ozone
  --Retune SBUV/2 ozone observation errors
  --Relax AMSU-A Channel 5 quality control
  --Update Community Radiative Transfer Model(CRTM) to version 
    2.0.2
  --Include field of view size/shape/power for radiative      
    transfer
  --Remove down weighting of collocated radiances
  --Limit moisture >= 1.e-10 in each outer iteration and at 
    end of analysis
  --Include uniform (higher resolution) thinning for satellite
    radiances
  --Improve location of buoys in vertical (move from 20m to 
    10m)
  --Improve Gridpoint Statistical Interpolation (GSI) code 
    with optimization and additional options
  --Recompute background errors
  --Inclusde SBUV from NOAA-19
  --Ambiguous vector quality control for ASCAT (type 290) data
 
Model Changes:
  --Set new thermal roughness length
  --Set minimum moisture value in Stratosphere to 1.0x10-7
  --Reduce background diffusion in the Stratosphere
 
Product Changes:
  -Correct error in the 192 hr, 12-hr precipitation bucket
 
The three model changes and the 192 hr precipitation change 
listed above are designed to address shortfalls introduced 
with the 27 July 2010 GFS resolution increase. The issues 
being addressed are:
 
  --increased low level warm bias over land
  --negative temperature bias in the stratosphere
  --negative wind speed bias in the stratosphere
  --error in the calculation of the 12 hr accumulated
    precipitation at 192 hrs only.
 
Data Availability:
 
The format and content of all GFS data sets will remain 
unchanged. GFS data is currently available on NOAAPORT, the 
NWS FTP server, the NCEP server and in NOMADS. The location 
of the data will remain unchanged.
 
Product delivery timing of the GFS products is not expected 
to change as a result of this implementation. More information 
regarding the GFS and associated products can be found at:
  
http://www.emc.ncep.noaa.gov/GFS/doc.php
  
A consistent parallel feed of data will become available on the 
NCEP server once the model is running in parallel on the NCEP 
Central Computing System by mid-March.  The parallel data will 
be available via the following URLs:
  
http://www.ftp.ncep.noaa.gov/data/nccf/com/gfs/para
 
ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/gfs/para
 
NCEP encourages all users to ensure their decoders are flexible 
and are able to adequately handle changes in content order, 
changes in the scaling factor component within the product 
definition section (PDS) of the GRIB files, and also any volume 
changes which may be forthcoming. These elements may change with 
future NCEP model implementations. NCEP will make every attempt 
to alert users to these changes prior to any implementations.
  
For questions regarding these changes, please contact: 
  
  John Derber
  NCEP/EMC, Global Climate and Weather Modeling Branch
  Camp Springs, Maryland
  301-763-8000 x 7740
  John.Derber@noaa.gov
 
  John H. Ward
  NCEP/EMC, Global Climate and Weather Modeling Branch
  Camp Springs, Maryland
  301-763-8000 x 7185
  John.Ward@noaa.gov
 
For questions regarding the dataflow aspects of these data 
sets, please contact:
 
  Rebecca Cosgrove
  NCEP/NCO Dataflow Team
  Camp Springs, Maryland 20746
  301-763-8000 x 7198
  ncep.list.pmb-dataflow@noaa.gov
 
NWS National Technical Implementation Notices are online at: 
 
  http://www.weather.gov/os/notif.htm
 
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