NOUS41 KWBC 281927
AAC
PNSWSH
Technical
Implementation Notice 11-10, Amended
National Weather
Service Headquarters Washington DC
225 PM EST Mon
Nov 28 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: Amended: Change to Wave Model Products:
Effective Date Postponed
Amended to
postpone this implementation until late December
or early January 2012 due to the need for
further evaluation.
In addition, due
to the large file size of the
multi_1.txxz.spec_tar file currently being disseminated
via the NCEP server, NCEP will begin making this
spectral output
file available in compressed format with the
filename
multi_1.txxz.spec_tar.gz. In a
future implementation in 2012,
the non-compressed file will be removed from the
NCEP server, so
NWS encourages
users to begin transitioning to the compressed
version now.
Effective January
2012 at a date to be determined, NCEP will
modify the spectral output grid products from the
Multi-grid
Global
Wave Model.
This model is run
using WAVEWATCH-III v3.14. Recent upgrades of
the model to v3.14 increased the spectral
resolution of the
model from a 25x24 spectral domain (frequency and
direction) to
a 50x36 domain. For backward compatibility,
however, the
spectral output from the model was kept at
25x24. This upgrade
will change the spectral output to match the
internal model
domain.
The key changes
are as follows:
1. The frequency
spectrum will now start from 0.035
(instead of
0.0412)
2. The
logarithmic increment will now be 1.07 (as opposed to
1.1). i.e., the next frequency will be 7%
higher as opposed
to 10% higher
earlier.
3. There will be
50 frequency components as opposed to the
earlier 25
frequency components (with the highest resolved
frequency being
0.963 as opposed to 0.406 earlier)
4. There will be
36 directional components as opposed to the
24 directional components
earlier. This means that the
directional
resolution will now be 10 degrees as opposed to
15 degrees earlier
The spectral
output files from these models are disseminated via
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 following
files will be affected:
akw.txxz.spec_tar
enp.txxz.spec_tar
multi_1.txxz.spec_tar
wna.txxz.spec_tar
where xx is the model cycle.
This change will
not affect the non-spectral output files from
these models.
The spectral products that are changing are not
available on NOAAPORT or in AWIPS.
Sample output
files reflecting this spectral resolution change
are available at:
ftp://polar.ncep.noaa.gov/pub/waves/devop/
Details about the
NCEP Multi-grid Wave Model are online at:
http://polar.ncep.noaa.gov/waves/index2.shtml
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@noaa.gov
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@noaa.gov
NWS National
Technical Implementation Notices are online at:
http://www.nws.noaa.gov/os/notif.htm
$$