NOUS41 KWBC 251256 AAB
PNSWSH
Technical Implementation Notice 10-44: Amended
National
Weather Service Headquarters
855 AM
EDT Mon Oct 25 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: Amended: Multi-Grid Hurricane Wave Model
Upgrade:
Rescheduled for November 2, 2010
NCEP is
postponing this implementation from October 26 to
November 2, 2010, to provide broader customer notification.
Effective
Tuesday, November 2, 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 multi-grid hurricane wave
model 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, the
same model version as NCEP’s 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
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
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
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
-New 10
arc min grid for the North Pacific regional waters
-New 10
arc min grid for the
-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
-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 at:
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
301-763-8000 x 7253
For
questions regarding the dataflow aspects of these data sets,
please contact:
Rebecca Cosgrove
NCEP/NCO Dataflow Team
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
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