2006/05/30
DM 04-06.08 Major changes to NCEP global ensemble products.
NOXX10 KWBC 191252
DATA MGT MESSAGE 04-06.08
TO AWIPS/NOAAPORT USERS.. FAMILY OF SERVICES/FOS/SUBSCRIBERS...
EMERGENCY MANAGERS WEATHER INFORMATION NETWORK /EMWIN/
NATIONAL WEATHER SERVICE /NWS/ CUSTOMERS... WAFS USERS...
GTS USERS... NWS FAX CHART USERS... NWS FTP USERS
FROM RTH WASHINGTON DATA MANAGEMENT
EFFECTIVE DATE MAY 30 2006, 12 UTC
The purpose of this message is to announce the routine availability of parallel data
at the NWS ftp server and to describe some changes to data locations described in
the earlier message on this subject.
Public data availability -
NCEP Central Operations is now making output from the parallel global ensemble
processing available on the NWS FTP server located at:
tgftp.nws.noaa.gov/SL.us008001/ST.opnt/MT.ensg_CY.{CC}/RD.{YYYYMMDD}/
These data are in the same format that will be implemented on May 30, 2006 for
the 12 UTC model cycle. Users of NCEP global ensemble products should use these
parallel data sets to modify their transfer routines to use these data. These data
will be continually updated at this location up to the implementation date. After
the May 30, 2006 implementation date the global ensemble data will only be available
at:
tgftp.nws.noaa.gov/SL.us008001/ST.opnl/MT.ensg_CY.{CC}/RD.{YYYYMMDD}/
MAJOR PRODUCT CHANGES TO NCEP GLOBAL ENSEMBLE OUTPUT -- PLEASE READ CAREFULLY
Starting with the 12 UTC cycle on 30 May 2006 NCEP Central Operations will implement
changes to the global ensemble processing that will result in drastic changes to its
products. These changes are necessary to allow us to:
1. Streamline our ensemble processing
2. Provide additional ensemble members at higher resolutions on public servers
3. Eliminate redundant global ensemble products on these servers.
These changes will impact products available on both the NCEP ftp server
(ftpprd.ncep.noaa.gov/pub/data/) and the NWS ftp server
(tgftp.nws.noaa.gov/SL.us008001/ST.opnl/). Users of these products will need to
modify their automated retrieval and processing routines so that they can continue
to receive and use these data.
The nature of these changes are as follows:
1. Directory Structure -
The directory tree of global ensemble data will be drastically changed to allow
for better system performance on the NCEP Central Computer System (CCS). This
change is being brought to the NCEP and NWS ftp servers as it will help with both
access times and directory listings.
On the NWS ftp server (tgftp.nws.noaa.gov) the directories will change as
follows:
Current -
tgftp.nws.noaa.gov/SL.us008001/ST.opnl/MT.ensg_CY.{CC}/RD.{YYYYMMDD}/PT.grid_DF.gr1/
New -
tgftp.nws.noaa.gov/SL.us008001/ST.opnl/MT.ensg_CY.{CC}/RD.{YYYYMMDD}/PT.grid_DF.gr1_RE.high/
-
tgftp.nws.noaa.gov/SL.us008001/ST.opnl/MT.ensg_CY.{CC}/RD.{YYYYMMDD}/PT.grid_DF.gr1_RE.low/
where CC = 00 or 12 and YYYYMMDD is the current date. The exact location of the
parameters you may need is given in item 3 below.
2. Six hourly output -
The global ensemble data sets will begin to be available in 6-hour increments
out through 384 hours. Currently 6-hour increment data are only available to 84
hours, then data are available in 12-hour increments to 384 hours.
3. Break Up of Pressure GRIB data sets (pgrb files) -
To facilitate the removal of redundant data sets the individual member ensemble
files are being broken up into two files per time step. The first file will contain
all of the parameters currently contained in the enspost format files (see Item 5
below) at one degree resolution out to 180 hours and 2.5 degree resolution from 186
to 384 hours. These are being termed the A files and this is an increase in their
resolution for the 90 to 180 hour time period. The second set (the B files) will
contain the rest of the parameters at one degree resolution to 84 hours and 2.5
degree resolution from 90 to 384 hours. This is the same resolution that these
parameters are currently made available.
On the NWS ftp server, the files will change as follows:
Current -
tgftp.nws.noaa.gov/SL.us008001/ST.opnl/MT.ensg_CY.{CC}/RD.{YYYYMMDD}/PT.grid_DF.gr1/fh.0024_pa.membrp01_tl.press_gr.onedeg
and
tgftp.nws.noaa.gov/SL.us008001/ST.opnl/MT.ensg_CY.{CC}/RD.{YYYYMMDD}/PT.grid_DF.gr1/fh.0384_pa.membrp01_tl.press_gr.2p5deg
- For the "A" files:
tgftp.nws.noaa.gov/SL.us008001/ST.opnl/MT.ensg_CY.{CC}/RD.{YYYYMMDD}/PT.grid_DF.gr1_RE.high/fh.0024_pa.membrp01_tl.press_gr.onedeg
and
tgftp.nws.noaa.gov/SL.us008001/ST.opnl/MT.ensg_CY.{CC}/RD.{YYYYMMDD}/PT.grid_DF.gr1_RE.high/fh.0024_pa.membrp01_tl.press_gr.2p5deg
- For the "B" files:
tgftp.nws.noaa.gov/SL.us008001/ST.opnl/MT.ensg_CY.{CC}/RD.{YYYYMMDD}/PT.grid_DF.gr1_RE.low/fh.0024_pa.membrp01_tl.press_gr.onedeg
and
tgftp.nws.noaa.gov/SL.us008001/ST.opnl/MT.ensg_CY.{CC}/RD.{YYYYMMDD}/PT.grid_DF.gr1_RE.low/fh.0384_pa.membrp01_tl.press_gr.2p5deg
This change will allow for a subset of higher resolution (one degree) data to be
available out to 180 hours, whereas today it is only available to 84 hours.
Parameter lists for the "A" and "B" files are located at:
http://www.nco.ncep.noaa.gov/pmb/changes/gefs_20060530_Alist and
http://www.nco.ncep.noaa.gov/pmb/changes/gefs_20060530_Blist
4. File Names Changing due to new ensemble transform mechanism -
When this change is implemented, NCEP will be creating perturbations in its
ensemble members via a ensemble transform breeding method. [For specific
information about this change, please see
http://wwwt.emc.ncep.noaa.gov/gmb/yzhu/html/ENS_IMP.html] Under this method, there
will no longer be positive and negative pairs of ensemble members. NCEP will
therefore cease identifying its members as either positive or negative and instead
use positive numbers for member identification. For example, on the NWS ftp server
the names will change as follows:
Current -
tgftp.nws.noaa.gov/SL.us008001/ST.opnl/MT.ensg_CY.{CC}/RD.{YYYYMMDD}/PT.grid_DF.gr1/fh.0024_pa.membrn01_tl.press_gr.onedeg
New - For the "A" files:
tgftp.nws.noaa.gov/SL.us008001/ST.opnl/MT.ensg_CY.{CC}/RD.{YYYYMMDD}/PT.grid_DF.gr1_RE.high/fh.0024_pa.membrp01_tl.press_gr.onedeg
- For the "B" files
tgftp.nws.noaa.gov/SL.us008001/ST.opnl/MT.ensg_CY.{CC}/RD.{YYYYMMDD}/PT.grid_DF.gr1_RE.low/fh.0024_pa.membrp01_tl.press_gr.onedeg
The names of these new files will range from fh.{FFFF}_pa.membrp01.* to
fh.{FFFF}_pa.membrp{NN}.*, where NN is the number of ensemble members. The control
run for all cycles will be named as fh.{FFFF}_pa.memberc00.*.
5. Removal of enspost Data Files -
To reduce product redundancy and to allow for the additional data sets outlined
in items number 2 and 3 above, the enspost (fh.xxxx.* files at NWS ftp) data sets
will no longer be produced. These data sets contain redundant information that is
already available in the pressure GRIB data sets. They are being removed and users
should instead use the "A" files located on the NWS ftp server at:
tgftp.nws.noaa.gov/SL.us008001/ST.opnl/MT.ensg_CY.{CC}/RD.{YYYYMMDD}/PT.grid_DF.gr1_RE.high/fh.{FFFF}_pa.membr{NNN}_tl.press_gr.onedeg
(where NNN is the member name, c00, p01-p10) and on the NWS ftp server at:
Even though these new "A" grids contain the same information as the enspost
(fh.xxxx.* files at NWS ftp) data sets, they are organized differently. The
existing files are created at the end of the ensemble processing and each file
contains information for a single parameter for all ensemble members and all
forecast hours. The new "A" files will be made available throughout the production
time of the ensemble processing on the NCEP CCS and they will each contain multiple
parameters for a single ensemble member and a single forecast hour.
6. Corrected ensemble extensions in GRIB1 PDS -
The current global ensemble data sets do not properly use the extended Product
Definition Section (PDS) of GRIB1. When this change is implemented the GRIB1 data
will be correctly labeled as ensemble data sets. This information is given in PDS
octets 41 and higher. A description of NCEP's use of these octets is given at:
http://www.nco.ncep.noaa.gov/pmb/docs/on388/appendixc.html
7. Removal of all GRIB index files -
The GRIB index files are no longer required by NCEP production and are being
removed from the ftp servers. These files are currently named as follows on the NWS
ftp server:
tgftp.nws.noaa.gov/SL.us008001/ST.opnl/MT.ensg_CY.{CC}/RD.{YYYYMMDD}/PT.grid_DF.gr1/fh.{FFFF}i_pa.membr{NNN}_tl.press_gr.{XXX}deg
If users still need GRIB index files, they can be created with NCEP software
located at:
http://www.nco.ncep.noaa.gov/pmb/codes/nwprod/util/sorc/grbindex.fd/
8. Removal of the 12 UTC "e2" Member -- Addition of Low Resolution Control Run for
all Four Cycles
With this implementation all four cycles per day will have a low resolution
control run. The need for the "e2" member at 12 UTC will go away at that time. The
NCEP CCS resources that were used to run the "e2" member will be used for the low
resolution control member. The low resolution control member data will be found at:
tgftp.nws.noaa.gov/SL.us008001/ST.opnl/MT.ensg_CY.{CC}/RD.{YYYYMMDD}/PT.grid_DF.gr1_RE.high/fh.{FFFF}_pa.membrc00_tl.press_gr.2p5deg
and
tgftp.nws.noaa.gov/SL.us008001/ST.opnl/MT.ensg_CY.{CC}/RD.{YYYYMMDD}/PT.grid_DF.gr1_RE.low/fh.{FFFF}_pa.membrc00_tl.press_gr.2p5deg
and
9. 6-hour Accumulations for Precipitation and Maximum and Minimum Temperature
In the current global ensemble system accumulation variables alternate between
6-hour and 12-hour amounts depending upon the forecast hour. With this upgrade all
accumulation amounts will be based on a 6-hour period.
Information on how these changes affect data on the NCEP ftp server can be
found at:
http://www.nco.ncep.noaa.gov/pmb/changes/
Please direct any questions on these changes to:
NCEP.List.PMB-PCSP@xxxxxxxx
Sincerely,
NCEP Central Operations.
THIS INFORMATION IS ALSO POSTED ON THE NWS DATA MANAGEMENT CHANGE
NOTICES WEB PAGE. THE URL IS LISTED BELOW.
http://weather.gov/datamgmt/index.html
DATA MANAGEMENT
TELECOMMUNICATION OPERATIONS CENTER
RTH WASHINGTON SENDS
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