Re: NCL doesn't recognize multiple accumulation periods in GRIB2 file

Hi Richard,

I have checked in a fix for this problem. The main issue was that
since the different accumulation periods are
split into separate variables after the initial count of variables in
the file, the variable count for the file as a whole
was not updated properly. This meant that variables at the end of the
file variable list were not accessible.

All NCL (as well as PyNIO) users of GRIB2 data should note that any
files with variables that have statistical variables
with multiple duration periods (recognizable as variables with
identical names except for the suffixes such as '_acc1hr',
'_acc3hr') may exhibit this problem. The inaccessible variables are
not necessarily the affected statistical variables,
but variables that happen to fall at the end of the list, which,
incidentally, is ordered based on the numerical values for
product template, discipline, category, and parameter number and
appear for each variable as the values for the
parameter_template_discipline_category_number attribute. See the GRIB
2 documentation
(http://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_doc.shtml) for
details.

Affected users may request a new binary by contacting Mary Haley.

Thanks, Richard, for bringing this problem to our attention.
  -dave

On Sep 17, 2008, at 1:24 PM, Richard Carpenter wrote:

> Hello,
>
>
>
> NCL doesn’t seem to recognize multiple accumulation periods in a
> GRIB2 file. I have a GRIB2 file with two records of accumulated
> precip for different periods. Wgrib2 output follows:
>
>
>
> 1:0:d=2008091709:APCP:surface:33-36 hour acc:
>
> 2:64724:d=2008091709:APCP:surface:30-36 hour acc:
>
>
>
> However, ncl_filedump shows only one instance:
>
>
>
> float APCP_P8_L1_GLC0_acc6h ( ygrid_0, xgrid_0 )
>
>
>
> It seems to pick one accumulation period in the file and disregard
> the others. Any idea what is going on? Thank you.
>
>
>
> Richard Carpenter
>
>
>
> _______________________________________________
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> ncl-talk_at_ucar.edu
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Received on Mon Sep 22 2008 - 18:12:24 MDT