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-------- Original Message --------
393
NOUS41 KWBC 091438
PNSWSH
Technical Implementation Notice 11-47
National Weather Service Headquarters Washington DC
938 AM EST Wed Nov 9 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
Chief, Science Plans Branch
Office of Science and Technology
Subject: Global Ensemble Forecast System (GEFS) Changes:
Effective January 24, 2012
On or about Tuesday, January 24, 2012, beginning with the 1200
Coordinated Universal Time (UTC) run, the NCEP Global Ensemble
Forecast System (GEFS) will be updated.
The upgrade in the GEFS production suite includes:
1. Running the latest Global Forecast System (GFS) model with
improved physics scheme GFS v9.1.0 to replace the currently used
GFS v8.0
2. Increasing the horizontal resolution from T190 (about 70km)
to T254 (about 50-55km) for the first 192 hours (8days) of model
integration
3. Increasing vertical resolution from 28 levels to 42 levels
for 0-384 hours (0-16 days) forecasts
4. Improving the ensemble initialization method by inflating the
initial perturbations between Earths surface and 500mb.
5. Optimizing the stochastic Total Tendency Perturbation (STTP)
scheme, implemented in February 2010 to represent model related
uncertainty by adjusting its parameters to match the increased
model resolution
Due to the increase in model resolution and limitations in
computational resources, the delivery of some GEFS products will
be delayed. Files for the early hours (06h forecast) will
experience virtually no delay. Files for the longer forecast
hours may be subject to a delay of up to 20 minutes depending on
the lead time. This change has been announced earlier this year
in a Public Information Statement. The delivery times of the GFS
and North American Ensemble Forecast System (NAEFS) products
will not be affected.
There will be several changes in the GEFS product data files
affecting files with names pgrba/pgrbb. The GEFS products
disseminated over NOAAPORT will not change in format or content.
The GEFS products disseminated via the NWS and NCEP servers will
have some changes in content. A small increase in the GRIB
product data volumes is expected due to these changes. These
products are available at the following locations:
NCEP server:
http://www.ftp.ncep.noaa.gov/data/nccf/com/gens/prod/gefs.YYYYMM
DD/xx
or
ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/gens/prod/gefs.YYYYMMD
D/xx , where YYYYMMDD is the date and xx is the model cycle
NWS server:
ftp://tgftp.nws.noaa.gov/SL.us008001/ST.opnl/MT.ensg_CY.xx/RD.YY
YYMMDD
Specific sub-directories and filenames on these servers will be
given for each product change below.
Product Additions:
1. Sunshine Duration (SUNSD) will be added to the following GEFS
output files for all forecast hours.
NCEP server:
pgrb2b/ge???.tHHz.pgrb2bf*
pgrb2blr/ge???.tHHz.pgrb2bf*.2
NWS server:
PT.grid_DF.gr2_RE.low/fh.xxxx_pa.membr*_tl.press_gr.onedeg
PT.grid_DF.gr2_RE.low/fh.xxxx_pa.membr*_tl.press_gr.2p5deg
2. Model surface (terrain) height will be added to the 204h
forecast file to reflect its change after the model truncation
at 192h. Note that the surface height in the 00h forecast files
(such as ge???.tHHz.pgrbaf00) is the terrain height used in the
model integration before the truncation at 192h.
NCEP server:
pgrb2a/ge???.tHHz.pgrb2af204
pgrb2alr/ge???.tHHz.pgrb2af204.2
NWS server:
PT.grid_DF.gr2_RE.high/fh.0204_pa.membr*_tl.press_gr.onedeg
PT.grid_DF.gr2_RE.high/fh.0204_pa.membr*_tl.press_gr.2p5deg
Product Removals:
Several parameters were mistakenly added to the 192 hour GEFS
products during a recent GFS upgrade. They will be removed with
this implementation. The parameters include:
1.12-hr Total Precipitation accumulation for the 180-192 hr
period
2. 12-hr Precipitation category fields, which include
categorical snow, ice pellets, freezing rain and rain, for the
180-192 hr period.
Changes 1 and 2 will affect the following files:
NCEP server:
pgrb2a/ge???.tHHz.pgrb2af192
pgrb2alr/ge???.tHHz.pgrb2af192.2
NWS server:
PT.grid_DF.gr2_RE.high/fh.0192_pa.membr*_tl.press_gr.onedeg
PT.grid_DF.gr2_RE.high/fh.0192_pa.membr*_tl.press_gr.2p5deg
3. 12-hr convective precipitation fields for the 180-192 hr
period
4. 12-hr averaged pressure fields at low/mid/high cloud bottom
over the 180-192 hr period
Changes 3 and 4 affect the following files:
NCEP server:
pgrb2b/ge???.tHHz.pgrb2bf192
pgrb2blr/ge???.tHHz.pgrb2bf192.2
NWS server:
PT.grid_DF.gr2_RE.low/fh.0192_pa.membr*_tl.press_gr.2p5deg
Fixes affecting inclusion of certain parameters:
Some diagnostic and anomaly fields have occasionally been
missing due to timing issues between post processing jobs. The
missing fields include 500 MB 5-wave geopotential height and its
anomaly, and 500 and 1000mb geopotential height anomaly. These
fields will now consistently be available in the following
files:
NCEP server:
pgrb2b/ge???.tHHz.pgrb2bf*
pgrb2blr/ge???.tHHz.pgrb2bf*.2
NWS server:
PT.grid_DF.gr2_RE.low/fh.xxxx_pa.membr*_tl.press_gr.onedeg
PT.grid_DF.gr2_RE.low/fh.xxxx_pa.membr*_tl.press_gr.2p5deg
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 early December. The parallel data
will be available via the following URLs:
http://www.ftp.ncep.noaa.gov/data/nccf/com/gens/para
or
ftp://ftpprd.ncep.noaa.gov/pub/data/nccf/com/gens/para
Test data are also available at:
ftp://ftp.emc.ncep.noaa.gov/gc_wmb/
Specific information regarding the scientific implementation can
be found at:
http://www.emc.ncep.noaa.gov/gmb/yzhu/html/imp/201109_imp.html
http://www.emc.ncep.noaa.gov/gmb/yzhu/imp/i201109/Q4_FY11_GEFS_S
cience_v4.pdf
NCEP encourages 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 Product Definition Section 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 implementation.
For questions regarding these changes, please contact:
Dingchen Hou
NCEP/EMC Global Modeling Branch
Camp Springs, Maryland
Phone: 301-763-8000 x7015
dingchen.hou@xxxxxxxx
For questions regarding the dataflow aspects of this dataset,
please contact:
NCEP/NCO Dataflow Team
Camp Springs , Maryland 20746
301-763-8000 x7198
ncep.list.pmb-dataflow@xxxxxxxx
NWS National Technical Implementation Notices are online at:
http://www.nws.noaa.gov/os/notif.htm
$$
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