[gradsusr] GRIB2 / GRIB1 Data

[Andrew Revering]

For the archives, I'm answering my own question as I think I got it
resolved.

 

The "Unknown Grib2 Index Version Number" occurs when I download NCEPs IDX
file with the GRIB2 file. However, if I create my own IDX file using
Gribmap, I don't get this error.

 

Additionally, the problem I was having with cnvgrib not working without
rebooting was due to cygwin1.dll being in more than one location on the PC.
Apparently you can only have 1 copy of this on the entire PC, and make sure
that it is in your system PATH.

 

With all this info in hand, I have switched to using Grib2 data directly,
bypassing the need for cnvgrib, which I think will resolve the last bit
where the data is occasionally 'funky' since an exact conversion from Grib2
to Grib1 can't really be done.

 

So my process is now this:

- DOWNLOADED GRIB2 FILE (NOT THE IDX FILE...THAT ONE FAILED TO WORK)

- CREATED CTL FILE BY RUNNING G2CTL... NOTE I HAD AN ERROR WITH CYGWIN,
FIXED BY MAKING SURE I ONLY HAD 1 COPY OF CYGWIN1.DLL ON THE ENTIRE MACHINE
(ONE COMES WITH OPENGRADS), AND THAT IT WAS IN THE SYSTEM PATH.

- THEN I RAN GRIBMAP TO CREATE THE IDX.

 

Andy

 

From: gradsusr-bounces at gradsusr.org [mailto:gradsusr-bounces at gradsusr.org]
On Behalf Of Andrew Revering
Sent: Sunday, October 31, 2010 4:27 AM
To: 'GrADS Users Forum'
Subject: [gradsusr] GRIB2 / GRIB1 Data

 

I have to type this out before my brain explodes and I forget everything..

 

I'm plotting some RUC model data. 

 

- When I try to create the CTL file off of a GRIB2 file using g2ctl and
display it in GrADS, GrADS gives me an error:                "Unknown Grib2
Index Version Number"

 

Ok, so I convert it to Grib1 then plot it.

 

- When I convert the Ruc GRIB2 to GRIB1 using cnvgrib, I have a hunch that
it's not converting the GRIB file correctly all the time because.

 

                1) If I manually try to execute cnvgrib.exe through a cmd
prompt (using windows) it seems it will occasionally get an error that is
resolved by rebooting the computer. The error says it could be a problem
with cygwin1.dll and it also suggests rebooting. so I reboot and try again
and it works.

                2) In my automated system that uses this Grib2->Grib1 step,
some data is good, and others are really odd. it seems like its missing data
or perhaps the data isn't even packed correctly. Other runs of data are
fine.

 

 

So with all that said I guess my questions are:

- Why does GrADS give me the "Unknown Grib2 Index Version Number" error if I
try to load a Grib2 file, and how do I work around that?

- Why would cnvgrib.exe not work without error unless I do a reboot of the
PC?

 

I'll also take any other ideas on how to load grib data so it is properly
read reliably.

 

 

 

Andrew Revering

Convective Development, Inc.

http://www.convectivedevelopment.com/

 

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://gradsusr.org/pipermail/gradsusr/attachments/20101102/e057dfee/attachment-0003.html