Re: Grib<-->NetCDF via GrADS

• To: netcdfgroup@xxxxxxxxxxxxxxxx
• Subject: Re: Grib<-->NetCDF via GrADS
• From: Arlindo da Silva <dasilva@xxxxxxxxxxxxxxxxxxxxx>
• Date: Wed, 13 Jan 1999 11:22:47 -0500 (EST)

Hi,

> 
> Some time ago, I talked with Russ Rew at Unidata about whether there
> was a utility for converting Grib data to netCDF, but the answer at
> that time was "no", at least not something that was general.  One
> concern was how to reconstitute 3D fields from the 2D slabs in Grib.
> 
> I recently learned of your "lats4d" GrADS script which, among other
> things, converts Grib data to netCDF.  I took a look at what lats4d
> produced and it looked pretty good!  I'm not sure how you solved the
> 2D-to-3D reconstitution, or if there are limitations on the variety
> of Grib files that lats4d will accept, but this certainly looks like
> a very useful capability.
>

Here is how it works. Given a GRIB file you have to create a grads
control (ctl) and grib map (gmp) files providing the necessary
metadata for GrADS to be able to read the GRIB file (I believe this is
the 2D-to-3D reconstruction you are referring to).  Usually GRIB files
produced by the NCEP re-analysis already come with these ctl and gmp
files. If not, there is a very nice perl utility called grib2ctl.pl which
automatically greates this metadata for you; see

     http://wesley.wwb.noaa.gov/grib2ctl.html

I have used grib2ctl for both NCEP and ECMWF GRIB files. 

> I am CC-ing Russ on this, but I was also wondering if you planned on
> passing this on to Unidata as "contributed" software?

I'd be more than glad to share this script with others. However, I am
still in the process  of improving LATS4D, so it may be better for
Russ to refer to the LATS4D page:

    http://dao.gsfc.nasa.gov/software/grads/lats4d/

BTW, lats4d can convert GRIB-->NetCDF/COARDS as well as
NetCDF/COARDS-->GRIB. More generally, it can convert any GrADS
redalble format (IEEE, GRIB, NetCDF or HDF-SDS) to GRIB, NetCDF, or
HDF-SDS. Although it uses GrADS, there is a sh(1) script which hides
this fact from you. You don't need to learn GrADS to use lats4d, but
you must have GrADS version 1.7beta9 or later installed on your
system.

I am trying to CC: this message to the netcdfgroup, although
most of my recent postings are being rejected since I have
no idea which e-mail address I am registered under.

  Cheers!

        Arlindo.

-- 
Arlindo da Silva
arlindo@xxxxxxxxxxxxxxxxxxxxx