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-------- Original Message --------
382
NOUS41 KWBC 161818
PNSWSH
Technical Implementation Notice 13-25
National Weather Service Headquarters Washington DC
218 PM EDT Fri Aug 16 2013
To: Subscribers:
-Family of Services
-NOAA Weather Wire Service
-Emergency Managers Weather Information Network
-NOAAPORT
-Other NWS Partners, Users and Employees
From: Tim McClung
Science Plans Branch Chief
Office of Science and Technology
Subject: Change to Great Lakes Wave Model Physics:
Effective October 1, 2013
On or about October 1, 2013, beginning with the 1200 Coordinated
Universal Time (UTC) cycle, the National Centers for
Environmental Prediction (NCEP) will introduce a physics upgrade
to the Great Lakes Wave Model, which will affect both the early
and late model runs GLW and GLWN.
The key changes for the Great Lakes system are as follows a new
physics package for wave growth under wind seas and for wave
dissipation due to wave breaking.
The new physics packages are outlined in Ardhuin et al. 2010. A
validation study made using NCEP's Great Lakes wave models is
presented in Alves et al., 2013 (see full reference below). The
latter work shows that the new physics significantly improves
model skill for wave height, especially in regions of strong
storm wind forcing. This will be reflected by crucial
improvements in forecast performance for extreme wave prediction,
a systematic problem in previous GLW/GLWN systems. Correction
will boost usage of the system by Great Lakes WFOs.All output
products will remain unchanged.
With this implementation, the location of the output data on the
ftp servers will be changed. Data are currently available in a
general directory named "wave." With this implementation, the
GLW and GLWN will be put in a directory named "glw." The full
directory paths are listed below.
The output data from these models will be disseminated on the
NCEP server at
http://www.ftp.ncep.noaa.gov/data/nccf/com/wave/prod/glw.YYYYMMDD
and
ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/wave/prod/glw.YYYYMMDD
and on NOMADS at
http://nomads.ncep.noaa.gov/pub/data/nccf/com/wave/prod/glw.YYYYM
MDD
where YYYYMMDD is the 4-digit year, month and day. Note that
prior to the implementation the data are available in
../com/wave/prod/wave...
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 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 early September. The parallel data will be available via the following URLs: http://www.ftp.ncep.noaa.gov/data/nccf/com/wave/para/glw.YYYYMMDD ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/wave/para/glw.YYYYMMDD 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 References: Alves et al., 2013: The Operational Implementation of a Great Lakes Wave Forecasting System at NOAA/NCEP. Weather and Forecasting, early online release: http://journals.ametsoc.org/doi/abs/10.1175/WAF-D-12-00049.1. 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 technical implementation notices are online at: http://www.nws.noaa.gov/om/notif.htm $$
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