NOUS41
KWBC 141210
PNSWSH
Service
Change Notice 10-42
National
Weather Service Headquarters
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
7220 NW 101ST Terrace
816-584-72048
ryan.l.Solomon@noaa.gov For questions about this change, or the WAFS Global
Grids data set, please contact:
Michael Pat Murphy
Warning Coordination Meteorologist
7220 NW 101ST Terrace
816-584-72048
National
Service Change Notices are online at:
http://www.nws.noaa.gov/om/notif.htm
$$
NNNN
|