Re: 20030530:decoders-gribtocdl-gribtonc

• To: Yan Gu <gu@xxxxxxxxxxxxx>
• Subject: Re: 20030530:decoders-gribtocdl-gribtonc
• From: Robb Kambic <rkambic@xxxxxxxxxxxxxxxx>
• Date: Mon, 2 Jun 2003 09:27:39 -0600 (MDT)

yOn Fri, 30 May 2003, Unidata Support wrote:

------- Forwarded Message

>To: netcdfgroup@xxxxxxxxxxxxxxxx,
>To: support@xxxxxxxxxxxxxxxx
>cc: Yan Gu <gu@xxxxxxxxxxxxx>
>From: Yan Gu <gu@xxxxxxxxxxxxx>
>Subject: Questions about decoders.
>Organization: UCAR/Unidata
>Keywords: 200305301540.h4UFegLd013006

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Hello, all,

I have some questions about the decoders provided by unidata.ucar.edu.
My question is related to the following two commands:

gribtocdl
gribtonc

First, for the "gribtocdl", it works well in my case. I got the following
message:

> gribtocdl -v Y63211 >gribtocdl.cdl
May 30 14:18:37 gribtocdl[286968]: Starting Up
May 30 14:22:49 gribtocdl[286968]: EOF on input
May 30 14:22:49 gribtocdl[286968]: Exiting
May 30 14:22:49 gribtocdl[286968]: 3008 WMO msgs, 3008 GRIBs decoded, 3008
written

My question is what the number "3008" stands for? And I knew that I can
use some tables when I create the cdl file, but I don't know how to create
the table.

Yan,

Usually many grib products relating to a model, etc  are all collected
into one file, the gribotcdl command acts on each product seperetely. The
above file contained 3008 products.  A product is a parameter such as
temperature, pressure, etc.  There is a man page for gribtocdl and
gribtonc that show the syntax of the special table files, they are
basically ascii files, ie.

        Grib;netCDF;long name               ;units;comments
         31 ;CI    ;Sea-ice cover           ;none ;(0-1)
         34 ;SSTK  ;Sea surface temperature ;K    ;
        151 ;MSL   ;Mean sea-level pressure ;Pa   ;
        167 ;T2M   ;2 metre temperature     ;K    ;

Second, for the "gribtonc", it also works well since there is no error
message. However we have question about the result netCDF file. It looks
like some useful information are lost. I mean, for some parameters, we
thought they should be there which they are not  based on the description
file. I have attached the cdl file from gribtocdl and the grib
header file from gribdump. Would you please help me out?

gribtonc will complain if a parameter is in the grib file but not in the
NetCDF file. So if you are not getting any error messages then the grib
file is being converted to NetCDF. Remember gribtonc preallocates space
for each record at one time, maybe the data is in a location that you may
not expect it to be entered. Use the NetCDF command ncdump to look at the
data.  Actually the raw grib file file is better for me to debug.  One way
to debug is from the command line, ie

% gribtonc -vl - grib.cdl output.nc < input.grib

This send the error messages to stdout.

Robb...




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