[nws-changes] 20111128: wave model products Fwd: ADMIN NOTICE NOUS41 KWBC

• To: nws-changes@xxxxxxxxxxxxxxxx
• Subject: [nws-changes] 20111128: wave model products Fwd: ADMIN NOTICE NOUS41 KWBC
• From: Linda Miller <lmiller@xxxxxxxxxxxxxxxx>
• Date: Mon, 28 Nov 2011 12:29:24 -0700

-------- Original Message --------

592
NOUS41 KWBC 281927
PNSWSH

Technical Implementation Notice 11-10, Amended
National Weather Service Headquarters Washington DC
227 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@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

NWS National Technical Implementation Notices are online at:

  http://www.nws.noaa.gov/os/notif.htm

$$