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000
NOUS41 KWBC 231555
PNSWSH

Technical Implementation Notice 14-46 Corrected
National Weather Service Headquarters Washington DC
1055 AM EDT Tue Dec 23 2014

To:        Subscribers:
           -Family of Services
           -NOAA Weather Wire Service
           -Emergency Managers Weather Information Network
           -NOAAPORT
           Other NWS Partners, Users and Employees

From:      Timothy McClung
           Chief, Science Plans Branch
           Office of Science and Technology

Subject:   Corrected: Global Forecast Systems (GFS) Update:
           Effective January 14, 2015

Corrected to:

-Notify users that on February 3, 2015, beginning with the 12 UTC
run, the decimal precision within two fields will be fixed
-Specify which files will be available for downloading
-Remove a variable from forecast hour 00.

Effective on or about January 14, 2015, beginning with the 1200
Coordinated Universal Time (UTC) run, the National Centers for
Environmental Prediction (NCEP) will upgrade the GFS Analysis and
Forecast System as follows:

  - Changes to the model components
  - Increases in horizontal resolution
  - Addition of 0.25 degree gridded output
  - Addition of new product fields
  - Change to product naming convention
  - Changes in product timeliness
  - Changes to downstream model impacts

1) Model changes to the GFS Global Spectral Model:

- Increase horizontal resolution of the first segment of the
forecast from Eulerian T574 (~27 km) to Semi-Lagrangian
T1534 (~13 km), and extend the length of forecast from
192 hours to 240 hours
- Increase horizontal resolution of the second segment of
the forecast from Eulerian T192 (~84 km) to semi-Lagrangian
T574 (~35 km), and set forecast time from 240 hours to 384
hours
- Change from Eulerian dynamics to Semi-Lagrangian dynamics,
which uses Hermite interpolation in both vertical and
horizontal directions.
- Use 5 minute daily Real-Time Global (RTG) Sea Surface
Temperature (SST) to replace 1.0 degree Reynolds 7 day SST
analysis
- Initialize ice at small inland lakes in the northern
hemisphere with 4 km Interactive Multi-sensor Snow and Ice
Mapping System (IMS) ice analysis data from the National Ice
Center. For large water bodies, use 5 minute NCEP/MMAB ice
analysis data to replace 30 minute ice data
- Use 1982-2012 5 minute SST climatology (replacing 1982-
2001 1 degree SST climatology).
- Use 1982-2012 30 minute sea ice concentration climatology
(replacing 1982-2001 1 degree climatology).
- Replace update of model snow depth by direct insertion of
AFWA depth data with a blend of the model first guess depth
and the AFWA depth.
- Use X-number to prepare spectral transform base functions:
X-number is a numerical technique that uses paired numbers
to represent real number to avoid computational underflow or
overflow that can occur in spectral truncation for wave
number larger than T1000.
- Use divergence damping in the stratosphere to reduce noise
- Add a tracer fixer for maintaining global column ozone
mass
- Use the Monte-Carlo Independent Column Approximation
(McICA) for Rapid Radiative Transfer Model (RRTM) Radiation
- Reduce drag coefficient at high wind speeds
- Use Hybrid Eddy-Diffusivity Mass-Flux Planetary Boundary
Layer (EDMF PBL) scheme and Turbulent Kinetic Energy (TKE)
dissipative heating
- Re-tune ice and water cloud conversion rates, orographic
gravity-wave forcing and mountain block; and reduce
background diffusion of momentum
- Add stationary convective gravity wave drag
- Modify initialization of forecast state variables to
reduce a sharp decrease in cloud water in the first model
time step
- Correct a bug in the condensation calculation after the
digital filter is applied
- Replace 1.0 degree bucket soil moisture climatology with
CFS/Global Land Data Assimilation System (GLDAS) climatology
at T574 (~27 km)
- Replace 1.0 degree momentum roughness length climatology
by using a look-up table based on vegetation type
- Add a dependence of the ratio of the thermal and momentum
roughness on vegetation type

2) Model changes to the GDAS/GFS Hybrid 3D-VAR Ensemble Kalman
Filter (EnKF) Data Assimilation:
- Increase EnKF resolution from T254L64 to T574L64
- Assimilate hourly GOES and EUMETSAT atmospheric motion
vectors
- Update radiance assimilation:
- Assimilate SSM/IS UPP LAS and Metop-B IASI radiances
- Use enhanced radiance bias correction scheme
- Update to version 2.1.3 of the Community Radiative
Transfer Model (CRTM).  CRTM v2.1.3 improves
specification of microwave sea surface emissivities.
This, in turn, improves the analysis of near surface
temperature over water, especially in the southern
oceans.
- Use stochastic physics in EnKF ensemble forecasts
- Change the dump window for GOES Satellite Wind (satwnd)
data from 1 hour to 6 hours. Subtypes will be added for
(NOAA/METOP AVHRR SATWIND) infrared cloud motion vector and
(NESDIS/GOES 3.9 micron channel) derived cloud motion vector

3) Output product changes

All filenames given are on the NCEP ftp server, the NCEP http
server, NOMADS, or the NWS ftp server, respectively, via
the following URLs (YYYYMMDD is the year, month and day; CC is
the cycle):

ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/gfs/prod/gfs.YYYYMMDDCC
/
ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/gfs/prod/gdas.YYYYMMDD
http://www.ftp.ncep.noaa.gov/data/nccf/com/gfs/prod/gfs.YYYYMMDDC
C/
http://www.ftp.ncep.noaa.gov/data/nccf/com/gfs/prod/gdas.YYYYMMDD
/
http://nomads.ncep.noaa.gov
ftp://tgftp.nws.noaa.gov/nfs/nwstg/ftp/SL.us008001/ST.opnl/MT.gfs
_CY.CC/RD.YYYYMMDD/


Product to be Removed

With this upgrade NCEP is removing obsolete or little used output
files. Please reference this html for explanations and possible
replacement products:

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

- The following files will be removed
      gfs.YYYYMMDDCC/gfs.tCCz.sstgrb
      gfs.YYYYMMDDCC/gfs.tCCz.engicegrb
      gfs.YYYYMMDDCC/gfs.tCCz.snogrb
      gdas.YYYYMMDD/gdas1.tCCz.engicegrb.grib2
      gdas.YYYYMMDD/gdas1.tCCz.sstgrb.grib2
      PT.grid_DF.gr2/fh.00xx_tl.press_gr.sstgrb
      gdas.YYYYMMDD/gdas1.tCCz.snogrb.grib2
      gfs.YYYYMMDDCC/gfs_grb211.tCCz.pgrbFH.grib2
      gfs.YYYYMMDDCC/gfs.tCCz.master.grbfFF.10m.uv.grib2
      PT.grid_DF.gr2/fh.xxxx_pa.sw10m_tl.press_gr.0p5deg
      gdas.YYYYMMDD/gdas1.tCCz.satang
      gfs.YYYYMMDDCC/gfs.tCCz.trmm.tm00.bufr_d
      gfs.YYYYMMDDCC/gfs.tCCz.sptrmm.tm00.bufr_d
      gdas.YYYYMMDD/gdas1.tCCz.sptrmm.tm00.bufr_d
      gdas.YYYYMMDD/gdas1.forecmwf.YYYYMMDDCC.grib2

- Remove variables from GFS and GDAS pressure GRIB files
(*pgrb*)
- Geopotential Height Anomaly (GPA)
- 5-Wave Geopotential Height Anomaly (5WAVA)
- Total Cloud Cover (TCDC) from forecast hour 00

Current Product Changes:

- The naming convention will change to include the grid and
3 digit forecast hours:

     On the NCEP server -
     GFS FH = anl or f000-f384
     GDAS FH = anl or f000-f009
      gfs.tCCz.pgrb2.fFFF -> gfs.tCCz.pgrb2.0p50.FH
      gfs.tCCz.pgrb2b.fFFF -> gfs.tCCz.pgrb2b.0p50.FH
      gfs.tCCz.pgrb.fFFF.grib2 -> gfs.tCCz.pgrb2.1p00.FH
      gfs.tCCz.pgrb2b.fFFF -> gfs.tCCz.pgrb2b.1p00.FH
      gfs.tCCz.pgrb.2p5deg.fFFF.grib2 -> gfs.tCCz.pgrb2.2p50.FH
      gfs.tCCz.pgrb.fFFF.grib2 -> gfs.tCCz.pgrb2.2p50.FH
      gfs.tCCz.goessimpgrb2fFFF.1p0deg ->
gfs.tCCz.goessimpgrb2FH.1p0deg
      gfs.tCCz.goessimpgrb2fFFF.grd221 ->
gfs.tCCz.goessimpgrb2FH.grd221
      master/gfs.tCCz.mastergrb2fFFF ->
gfs.tCCz.pgrb2full.0p50.FH
      gdas1.tCCz.pgrbfFF.grib2 -> gdas1.tCCz.pgrb2.1p00.FH

     On the NWS server:
     GFS FH = 000-384
      fh.0FH_tl.press_gr.0p5deg -> fh.0FH_tl.press_gr.0p50deg
      fh.0FH_tl.press_gr.1p0deg -> fh.0FH_tl.press_gr.1p00deg
      fh.0FH_tl.press_gr.2p5deg -> fh.0FH_tl.press_gr.2p50deg

- The following files will have decreased forecast hour
availability to now only:
      gfs.YYYYMMDDCC/gfs.tCCz.bfFF hourly from 00-12
      gfs.YYYYMMDDCC/gfs.tCCz.sfFF hourly from 00-12, 3hly to 24

- There are numerous changes to the operational NOMADS
files. For all of the details please reference this page:

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

- The packing for GRIB2 will be switched to second order
complex packing. The benefits for users will be much faster
IO time compared with the existing JPEG packing. The second
order packing provides good accuracy, although files will be
slightly larger than JPEG packing.

- With this upgrade output files are being written directly
to GRIB2 instead of first being written out to GRIB1 and
converted to GRIB2. Users may see some differences with the
encoding and are encouraged to upgrade their software to
handle this. Please see the links below for upgraded code:

http://www.nco.ncep.noaa.gov/pmb/codes/GRIB2
http://www.cpc.ncep.noaa.gov/products/wesley/wgrib2
ftp://ftp.cpc.ncep.noaa.gov/wd51we/wgrib

- Modify the list of stations for which BUFR data is
generated for the GFS.  The changes will also modify the
lists of stations in the GFS BUFR sounding collectives
disseminated on NOAAPORT. For the full list please reference
this page:

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

- Use of the enhanced radiance bias correction scheme will
be changing the abias file. The format of the file is being
changed to incorporate information from the satang file.
      gdas.YYYYMMDD/gdas1.tCCz.abias

- The GFS cyclone tracker file code has changed from NA to
AA for storms in the Arabian Sea.
 PT.text_GP.tratcf/cyclone.trackatcf

- The clear sky UV radiation reaching the surface (CDUVB)
and the cloudy sky UV radiation reaching the surface (DUVB)
are being outputted as integer values. On Feb 3, 2015 with
the 12 UTC cycle these variables will be fixed to have real
values with 0.1 precision.

- Change variables averaged or accumulated over time, such
as precipitation accumulation, to 6 hourly up to forecast
hour 240 for all products (some had been 12 hourly after
forecast hour 180 and some had been 12 hourly after forecast
hour 192).

- Modify fields to both GFS and GDAS:
- Add Frozen Precipitation Fraction (CPOFP)
- Add Ozone (O3MR) at 150, 200, 250, 300, 350, and 400 mb
- Add Dew Point (DPT) at 2 meters
- Add Apparent Temperature (APTMP)
- Add Membrane SLP in GDAS pressure grib files
- Rename TMP at 0-0.1 m, 0.1-0.4 m, 0.4-1.0 m, and 1-2 m
to the more accurate name of Soil Temperature (TSOIL)
- Modify the precision of Relative Humidity (RH) grids
- Modify GRIB encoding level of Total Cloud Cover (TCDC),
removing "considered as a single layer"
- Move Snow Depth (SNOD) from the *pgrb2b* files into the
*pgrb2* files

New Products:

- Produce GRIB2 output at the highest resolution on 0.25
degree latitude-longitude grid 193 (1440x721)
      gfs.YYYYMMDDCC/gfs.tCCz.pgrb2.0p25.FH
      gfs.YYYYMMDDCC/gfs.tCCz.pgrb2b.0p25.FH

Product Timeliness:

GFS product delivery timing on NOMADS, the ftp server and
NOAAPORT will be delayed for numerous products. Pressure GRIB
(*pgrb*) files will be as much as 20 minutes delayed. Please
reference this page for a full list of delays:

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


NOAAPORT/SBN product changes:

- Additional forecast hours 186, 198, 210, 222, and 234 will
be added for the following GRIB2 grids only. There are no
new headers to add as these grids use existing headers:
201 - 381km Northern Hemisphere
212 - 40km CONUS
213 - 95km CONUS
160 - 47.5km Alaska
161 - 0.5 degree lat/lon for Puerto Rico
254 - 40km Pacific Region

- Variables averaged or accumulated over time, such as
precipitation, will now be valid over a 6 hour period for
forecast hours 180 through 240, rather than a 12 hour
period. There are no new headers to add as these new grids
use existing headers.

4) Downstream model impacts

There are impacts to downstream GFS models and their product
output. Please reference this page for more information on the
following:

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

- GFS-based Model Output Statistics (MOS) products
- Global Ensemble Forecast System variable change
- Numerous downstream model output timeliness changes. These
changes impact both NOAAPORT/SBN and the NCEP/NWS servers.

5) Parallel data available

Due to system constraints the parallel GFS will run on the backup
supercomputer. This will cause impact to output availability on
at least 3 days due to mandatory maintenance. We will notify
users when a cycle will not be available through this user list:

https://lstsrv.ncep.noaa.gov/mailman/listinfo/ncep.list.nomads-
ftpprd

Starting in late October all parallel data sets will be available
on the following servers:

ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/gfs/para/gfs.YYYYMMDDCC
/
ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/gfs/para/gdas.YYYYMMDD
http://www.ftp.ncep.noaa.gov/data/nccf/com/gfs/para/gfs.YYYYMMDDC
C/
http://www.ftp.ncep.noaa.gov/data/nccf/com/gfs/para/gdas.YYYYMMDD
/
http://nomads.ncep.noaa.gov

NCEP has a full list of products that will be available for
download from both the NCEP and NWS servers as well as NOMADS.
You can find the file names and their inventory through the
following http page:

http://www.nco.ncep.noaa.gov/pmb/products/gfs/index.shtml.upgrade


For more information on this GFS upgrade, please see EMC real-
time and retrospective parallels and verification pages:

http://www.emc.ncep.noaa.gov/gmb/wx24fy/vsdb/gfs2015/
http://www.emc.ncep.noaa.gov/gmb/wd20rt/
http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/

NCEP urges all users to ensure their decoders can handle changes
in content order, changes in the scaling factor component within
the product definition section (PDS) of the GRIB files, and
volume changes. These elements may change with future NCEP model
implementations. NCEP will make every attempt to alert users to
these changes before implementation.

For questions regarding these changes, please contact:

     Mark Iredell
     NCEP/Global Climate and Weather Modeling Branch
     College Park, MD
     301-683-3739
     Mark.Iredell@noaa.gov

For questions regarding the data flow aspects of these data sets,
please contact:

     Carissa Klemmer
     NCEP/NCO Dataflow Team
     College Park, MD
     301-683-0567
     ncep.list.pmb-dataflow@noaa.gov

NWS National Technical Implementation Notices are online at:

   http://www.nws.noaa.gov/os/notif.htm

$$



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