ggrib v2.0 --Extraction of geographic subdomains from GRIB-1
files
A program for extraction of geographic subdomains from GRIB files
now exists. Comments are appreciated, future versions may appear.
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By v1.0 ggrib tackles global files and a subdomain that crosses
the discontinuity (called the branch cut among math freaks, geophysicists
place the discontinuity at 0 or 180o longitude, whichever is
more convenient). If lon1==lon2, ggrib will attempt to
reproduce global grids where the discontinuity has been moved to lon1.
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The grid MUST be in geographic coordinates (lon,lat). The grid organization
is arbitrary, but it is recommended that the ECMWF standard be adhered
to (first grid point in NW corner, adjacent grid points in east-west direction).
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By v1.0 the original binary representation together with bitmap section
(if present) is retained.
-
By v2.0 dots can be substituted for bounding coords, in which case the
original grid boundaries will be used (see example 3).
-
By v2.0 specifying bounding coords that go beyond the original grid boundaries
will not produce an error but will quietly be adjusted to the original
grid boundaries.
Syntax:
ggrib gribfile newgribfile westlon southlat eastlon northlat
Example:
ggrib world.grb smallworld.grb -10.0 45.0 35.0 70.0
Produces an excerpt from a global file with bounding coordinates (10W,45N)
and (35E,70N).
Example 2:
ggrib world.grb smallworld.grb -170.0 45.0 -170.0 70.0
Produces a zonal "ribbon" from 45N to 70N that extends around the globe.
Example 3:
ggrib oldworld.grb bravenewworld.grb -20 . . 75
Prodcues a new grid which extends from 20W to the eastern rim of the
old grid, takes the southern latitude of the old grid and goes to 75N.
Installation:
tar xvf ggrib.tar
cd ggrib
make -f ggrib.make
The library gribw must be compiled in advance using gribwlib.make.
This software along with the other files listed in ggrib.make
are all contained in the tape archive gribw.tar found at ftp://ftp.cpc.ncep.noaa.gov/wd51we/gribw.
--
Oyvind Breivik, Norwegian Meteorological Institute, www.dnmi.no
Marine Forecasting Centre, Alleg 70, N-5007
Bergen, Norway
Office: +47-55236623 Fax: +47-55236703
Mob: +47-48115241
Switchboard: +47-55236600 Home: +47-55314171
|
www.nws.noaa.gov 
