NOTE: The nws-changes mailing list is no longer active. The list archives are made available for historical reasons.
-------- Original Message --------
109
NOUS41 KWBC 141210
PNSWSH
Service Change Notice 10-42
National Weather Service Headquarters Washington DC
810 AM EDT Thu Oct 14 2010
To: Subscribers:
-Family of Services
-NOAA Weather Wire Service
-Emergency Managers Weather Information Network
-NOAAPort
Other NWS partners and employees
From: Cynthia Abelman
Chief, Aviation Services Branch
Subject: Change in Format of Experimental World Area
Forecast System Gridded Forecasts of Icing,
Clear Air Turbulence (CAT) and Cumulonimbus
Cloud (Cb): Effective November 18, 2010
Effective Thursday, November 18, 2010, at 0000 Coordinated
Universal Time (UTC), the NWS will cease GRIB1 format
production of the Experimental World Area Forecast System
(WAFS) Global Grids of Icing, Clear Air Turbulence and
Cumulonimbus Clouds. At that time the Experimental WAFS
Global Grids of Icing, Clear Air Turbulence and
Cumulonimbus Clouds will be produced only in GRIB2 format.
The GRIB2 format was developed by the World Meteorological
Organization (WMO). It is a binary format which contains
gridded data. The name GRIB comes from Gridded Binary.
GRIB2 was approved for experimental use by the WMO/CBS in
1998 and for operational use in 2000. It addresses the
problem of GRIB1 tables being full and no longer capable of
expansion/extension. GRIB2 introduced a more comprehensive
parameter identification system and expanded use of
templates.
There are some differences at the technical encoding level
between GRIB1 and GRIB2. The major differences from the
meteorological and operational perspective between the two
formats are as follows:
a) GRIB2 is a regular grid with 1.25 X 1.25 degree
(approximately 140KM X 140 KM at the equator)
resolution.
GRIB1 has the longitudinal points on the grid
thinned as the polar regions are approached.
b) GRIB2 bulletins contain data covering the entire
globe for each level and parameter in each
bulletin. GRIB1 has separate bulletins for each
octant of every level/parameter combination.
c) GRIB2 data is compressed using the JPEG2000
standard. JPEG2000 decompression libraries will
be necessary.
d) GRIB2 has a temporal resolution of 3 hours, from
T+06 to T+36 inclusive. GRIB1 has a temporal
resolution of 6 hours: T+06 to T+36 inclusive.
e) GRIB2 has additional levels close to the normal
cruise level of Airliners.
The Experimental GRIB2 WAFS Global Grids for Icing, Clear
Air Turbulence and Cumulonimbus Cloud will only be
available at the WAFS Internet File Service (WIFS):
http://aviationweather.gov/wifs/
Experimental GRIB2 Icing, Clear Air Turbulence and
Cumulonimbus Cloud grids will be in a file folder labeled
Trial Forecasts. The remainder of the operational WAFS
Global Grids (i.e., temperature, wind, etc.) will remain
available via WIFS in GRIB1 and GRIB2 format. No changes
are being made to the WMO headers for these experimental
products.
For technical questions and support in registering a user
account at the WIFS website or downloading and accessing
the GRIB2 data, contact:
Ryan Solomon
Aviation Weather Center
7220 NW 101ST Terrace
Kansas City, MO 64153
816-584-72048
ryan.l.Solomon@xxxxxxxx
For questions about this change, or the WAFS Global Grids
data set, please contact:
Michael Pat Murphy
Warning Coordination Meteorologist
Aviation Weather Center
7220 NW 101ST Terrace
Kansas City, MO 64153
816-584-72048
michael.pat.murphy@xxxxxxxx
National Service Change Notices are online at:
http://www.nws.noaa.gov/om/notif.htm
$$
NNNN
nws-changes archives: