To users of GRIB files:
Since Enomoto Takeshi brought up an NCL/GRIB question, I thought it
would be a good time to announce some major upgrades we've made to
NCL's GRIB reading capability. These capabilities will be available in
the next minor release of NCL (version 4.2.0.a028, a few weeks away),
but a beta version is available now if you want to test it. (See
details below.)
Here are some of the new capabilities and changes:
The ability to load GRIB parameters from a file has been
added. This can be done by setting the environment variable
NCL_GRIB_PTABLE_PATH to a file or directory path. Parameter tables
read from a file have precedence over built-in tables that would
otherwise apply to the same dataset. An interface for adjusting
this precedence at run-time is on the enhancement request list.
Many new built-in parameter tables were added, including all files
supported by wgrib (http://wesley.wwb.noaa.gov/wgrib.html), three
Forecast Systems Laboratory tables, and a Navy Fleet Numerical
Meteorology and Oceanography Center table. Support was also added
for thinned "quasi-regular" grids.
The way NCL names certain GRIB variables has been changed. This
may result in variable names that are incompatible with previous
names. In particular, variables involving average, accumulation,
and difference over specific periods of time. For example, the
variable "PRATE_GDS4_SFC_ave" will now be
"PRATE_GDS4_SFC_ave6h". This was required because some GRIB files
have averages for several differing periods on the same file.
A problem was fixed for parameters less than 128 in ECMWF files.
If you are interested in helping us to beta test these new
capabilities, please send me email (haley AT ucar.edu) and let me know
what kind of system you have. We will send you more information about
these new capabilities and a binary to try.
Or, if you like, you can provide us with GRIB files to test.
We appreciate your feedback and help on this!
Cheers,
--Mary Haley
NCL Project Coordinator
NCAR/SCD/VETS
1850 Table Mesa Drive
Boulder, CO 80305
haley AT ucar.edu
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