Re: 20020410: gribtonc CDLs for AVN and could CDL for LAPS work

• To: Tiziana Cherubini <tiziana@xxxxxxxxxx>
• Subject: Re: 20020410: gribtonc CDLs for AVN and could CDL for LAPS work
• From: Robb Kambic <rkambic@xxxxxxxxxxxxxxxx>
• Date: Tue, 18 Jun 2002 12:44:58 -0600 (MDT)

On Mon, 17 Jun 2002, Tiziana Cherubini wrote:

On Mon, 17 Jun 2002, Robb Kambic wrote:

> Tiziana,
>
> I made some changes to the gribtonc source, now it appears that the
> variables are being written.  It kind of hard to tell because some of the
> variables values are missing and or have very little data.

Hi Robb,

thanks very much for the new decoders package. I tried it
but, I'm sorry to say, that, even if in the log file the
variable list is now complete, therefore all variables are
being written, still some fields (i.e. P_lctl or crain and
many others) are filled with missing values whereas they
are present in the original grib file.

Tiziana,

As I stated yesterday, many of the initial values are missing. If you look
at the whole set of values returned the data is there.  I checked it
against the data file you suggested the other day.  To look at a
particular variable, use the -v flag on ncdump. ie.

% ncdump -v P_hctl avn.nc | more

> I did get the above ftp file to use as a test case.

Have you been able to produce a netcdf file with all the
fields filled with the proper values?

There is also something about the size of the file produced
by the gribtonc that is not really clear to me.
The original grib files, say:

-rw-r--r--    1 tiziana  users    22830364 Jun 14 08:58 gblav.t12z.pgrbf00
-rw-r--r--    1 tiziana  users    25809992 Jun 14 09:00 gblav.t12z.pgrbf06

where the first one is basicly the analysis file at 12:00 UTC
and the second one is the t+6h forecast based on the 12:00 UTC
analysis

are almost 3M far apart in size. After running the gribtonc
I obtain:

-rw-r--r--    1 tiziana  users    116794932 Jun 17 14:05 gblav.t12z.f00.nc
-rw-r--r--    1 tiziana  users    233561716 Jun 17 13:39 gblav.t12z.f06.nc

the second one is now almost the double in size than the
first one. Would you expect it?

That's because the NetCDF file preallocates all the space it needs.  Since
the second file has 2 forecasts, it's twice the size.  Even if there is
only one variable that has 2 records.  This is a con of NeCDF but because
the space is preallocated, it makes for quick access of the data.  There
still seems to be a problem with gribdump though, working on it.

Robb...

Thanks a lot for your help,

                                Tiziana.

> I made new tar.Z file that's located in the ftp dir
> pub/decoders  it's called  decoders-2.3.9.tar.Z
>
> Let me know if this solves your problems.
>
> Robb....
>
>
> > although they are listed in the CDL you provided to me
> > (see mail below). I can easyly convert grib analysis
> > files but I'm still having problems with the forecast ones.
> >
> > Thanks a lot,
> >
> >               Tiziana.
> >
-------------------------------------
Tiziana Cherubini
Department of Meteorology
University of Hawaii
2525 Correa Rd. HIG 367
Honolulu, Hawaii 96822
(808) 956-4593, (808) 956-2877 fax

==============================================================================
Robb Kambic                                Unidata Program Center
Software Engineer III                      Univ. Corp for Atmospheric Research
rkambic@xxxxxxxxxxxxxxxx                   WWW: http://www.unidata.ucar.edu/
==============================================================================