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-------- Original Message --------
306
NOUS41 KWBC 281909
PNSWSH
Technical Implementation Notice 12-17
National Weather Service Headquarters Washington DC
310 PM EDT Wed Mar 28 2012
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: Change to Wave Model Physics:
Effective Date May 8, 2012
Effective on or about Tuesday, May 8, 2012, beginning with the
1200 Coordinated Universal Time (UTC) run, the National Centers
for Environmental Prediction (NCEP) will introduce a physics
upgrade and a few minor product changes to the Multi-grid Global
Wave Model.
This model is currently run using WAVEWATCH-III v3.14. The wave
model will be upgraded to WAVEWATCH-III v4.5.1, which introduces
several new physics packages to the wave model. The key changes
are as follows:
1. A new physics package for wave growth under wind seas
2. A new physics package to account for swell dissipation for
swells propagating long distances.
3. A new physics package for wave dissipation due to wave
breaking.
The new physics packages are outlined in Ardhuin et. Al. 2010
(see full reference below). Validation studies show that the new
physics significantly improve model skill for wave height,
especially in regions of strong swells such as the Pacific.
The majority of the output products will remain unchanged. The
number of stations available in the point output products will be
reduced by 112. The stations that are being removed are -
WALLOPS_?? (?? ranging from 01 to 61) and SANCLEM_?? (?? ranging
from 01 to 51). These stations were added in an experimental mode
and are now being removed. In addition, the spectral output files
will now be compressed due to their large sizes. The
uncompressed files, including the multi_1.txxz.spec_tar file (xx
is the model cycle) will be removed from the NCEP server. Any
downstream users actively using these spectral output files will
need to adapt their software to use the compressed versions. Note
that the tar files are being compressed, the individual spectral
files inside the respective tarballs will not be compressed.
The output data from these models are disseminated on the NCEP
server at
http://www.ftp.ncep.noaa.gov/data/nccf/com/wave/prod/
and
ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/wave/prod/
The files that will be compressed are
akw.txxz.spec_tar becomes akw.txxz.spec_tar.gz
enp.txxz.spec_tar becomes enp.txxz.spec_tar.gz
wna.txxz.spec_tar becomes wna.txxz.spec_tar.ga
The file multi_1.txxz.spec_tar will be removed. The file
multi_1.txxz.spec_tar.gz has been available on the server for
some time.
Sample output files from the new physics are available at
ftp://polar.ncep.noaa.gov/pub/waves/develop/
Details about the NCEP Multi-grid Wave Model are online at:
http://polar.ncep.noaa.gov/waves/index2.shtml
These changes will only correspond to the global wave model
(multi_1). Upgrade of the hurricane wave model (multi_2) will
occur at a later date.
A consistent parallel feed of data will be available on the NCEP
server once the model is running in parallel on the NCEP Central
Computing System in late March. The parallel data will be
available via the following URLs:
http://www.ftp.ncep.noaa.gov/data/nccf/com/wave/para
ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/wave/para
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, changes
to the GRIB Bit Map Section (BMS), 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 model changes, please contact:
Hendrik Tolman
NCEP/Marine Modeling and Analysis Branch
Camp Springs, Maryland
301-763-8000 ext 7253
hendrik.tolman@xxxxxxxx
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@xxxxxxxx
Reference: Ardhuin, F. et. al., 2010: Semi-empirical dissipation
source functions for ocean waves: Part 1, definition, calibration
and validation. J. Phys. Oceanogr., 40, 1917 - 1941.
NWS National Technical Implementation Notices are online at:
http://www.nws.noaa.gov/os/notif.htm
$$
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