NOUS41
KWBC DDHHMM AAB
PNSWSH
Technical
Implementation Notice 11-07, Amended
National
Weather Service Headquarters
304 PM EDT Fri May 6 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:
Amended: Global Forecast System (GFS) Upgrade:
Effective May 9, 2011
Amended to change the implementation to as early as
Monday, May 9 with the 1200 UTC model cycle. A determination will be made
on Monday May 9. There is a high likelihood that Tuesday, May 10, will be declared
a Critical Weather, preventing this GFS implementation from proceeding for
indeterminate time. The NCEP Senior Duty Meteorologist will issue a NOUS42
administrative message when the implementation has taken place.
Amended to reschedule the implementation from April 26,
2011, to May 10, 2011 to allow for a full evaluation period. Also amended to include details of a new sea level
pressure field being added to select products available via the ftp servers.
Effective
May 10, 2011, beginning with the 1200 Coordinated
Universal
Time (UTC) run, the National Centers for Environmental
Prediction
(NCEP) will upgrade the 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
--Include 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
-Addition of a new membrane sea level
pressure (SLP) field to
the 0.5, 1.0 and 2.5 degree pressure grib (pgrb) files only.
This
pressure is generated by first relaxing the underground
virtual temperature and then integrating the hydrostatic
equation downward. The field will be subject to Spectral
Gibsing near the coast, but this will be addressed in a
future
implementation.
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, with the exception of the addition of the new
SLP field. 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
301-763-8000 x 7740
John H. Ward
NCEP/EMC, Global Climate and Weather Modeling Branch
301-763-8000 x 7185
For
questions regarding the dataflow aspects of these data
sets, please contact:
Rebecca Cosgrove
NCEP/NCO Dataflow Team
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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