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-------- Original Message --------
564
NOUS41 KWBC 311330
PNSWSH
Technical Implementation Notice 10-44
National Weather Service Headquarters Washington DC
930 AM EDT Tue Aug 31 2010
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: Multi-grid Hurricane Wave Model Upgrade:
Effective October 19, 2010
Effective Tuesday October 19, 2010, beginning with the 1200
Coordinated Universal Time (UTC) run, the National Centers for
Environmental Prediction (NCEP) will implement a new Hurricane
Wave Model. This will be a multi-grid hurricane wave model and
will replace the existing North Atlantic Hurricane (NAH) and
North Pacific Hurricane (NPH) wave models. The model upgrade
will result in a change of 27 minutes to the product
dissemination time and the generation of new products.
Details of these changes are outlined below.
Model Changes:
Instead of two separate models, the hurricane wave model will now
be a single model with multiple two-way nested grids. The new
multi-grid hurricane wave model will use WAVEWATCH-III v3.14,
which is the same model version as NCEPs Global Multi-grid Wave
Model (the current NAH and NPH use WAVEWATCH-III v 2.22). The
upgrade to version 3.14 will result in the following:
- Upgraded shallow water physics, which accounts for shallow
water processes such as wave breaking. Together with the
increased wave resolution in coastal regions, this change will
provide a better representation of wave physics in land
falling hurricanes.
- Increasing internal model spectral resolution to 50 components
in frequency and 36 components in direction. Spectral output
at the points will continue to be 29 components in frequency
and 24 components in direction.
- Adding a new algorithm to partition the spectral
energy into wind wave, primary and secondary swells. Spectral
parameters for these different fields (wave height, peak
period and direction) will be part of the model output on the
new grids listed below. These fields will not be added to the
existing NAH and NPH products.
Wind forcing for the global, Alaskan and Pacific Island grids
will be from the Global Forecast System (GFS) winds while all the
other grids will be a blend of the GFS and GFDL hurricane model
winds, as is currently done in the NAH and NPH. The only
exception is the Hawaiian Islands, part of the Pacific Island
grid, which also will have a blend of GFS and GFDL hurricane
model wind forcings.
Product Changes
As a result of this upgrade, all of the output products from the
new multi-grid hurricane model will be disseminated 27 minutes
later than the current NAH and NPH output products. Any concerns
with this change in product dissemination time should be directed
to the contact points listed below.
The output grids from the multi-grid hurricane wave model will be
as follows:
Products with 25x24 spectral resolution:
-Current 0.25 degree NAH grids
-Current 0.25 degree NPH grids
Products with 50x36 spectral resolution:
-New 0.5 degree global domain grid
-New 0.25 degree regional domain for North Atlantic (domain
corresponds to current NAH grid)
-New 0.25 degree regional domain for North Pacific (domain
corresponds to current NPH grid)
-New 10 arc min grid for the North Atlantic regional waters
-New 10 arc min grid for the North Pacific regional waters
-New 10 arc min grid for the Pacific Islands and Hawaii
-New 10x15 arc min grid for the Alaskan waters
-New 4 arc min grid for the US East Coast
-New 4 arc min grid for the US West Coast (including the
coastal waters of Hawaii)
-New 8x4 arc min grid for the Alaskan coast
NCEP will continue to produce the current NAH and NPH output
products, including their respective point output files, until
further notice. These products will be generated using output
from the new multi-grid hurricane wave model.
The new grids will be disseminated via the NCEP server and will
be incorporated into AWIPS on a yet-to-be-determined date. More
details about the NCEP Multi-grid Hurricane Wave Model are
available at:
http://polar.ncep.noaa.gov/waves/index2.shtml
A consistent parallel feed of data will become available on the
NCEP server once the model is running in parallel on the NCEP
Central Computing System, around September 7, 2010. At this time
the parallel data will be available via the following URL:
http://www.ftp.ncep.noaa.gov/data/nccf/com/wave/para
or
ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/wave/para
Users should ensure their decoders are flexible and are able to
adequately handle changes in content, parameter fields changing
order, changes in the scaling factor component within the Product
Definition Section (PDS) of the GRIB files, and any volume
changes that may occur. These elements may change with future
NCEP model implementations. NCEP will make every attempt to alert
users to these changes prior to any implementation.
For questions regarding these model changes, please contact:
Hendrik Tolman
NCEP/Marine Modeling and Analysis Branch
Camp Springs, Maryland
301-763-8000 x 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
$$
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