Re: 20031022:GRIB2 to netCDF

On Wed, 22 Oct 2003, Tom Whittaker wrote:

>  >>>Keywords: 200310221429.h9METkOb014773
>
> Hi Robb...
>
> Thanks for your info.  Actually, I'm in an email discussion with NWS about
> NDFD grid distribution and wanted to let them know that GRIB2 is currently an
> issue for our community.
>
> I'm still trying to get them to understand that we don't always want to have
> to ftp complete files, convert them into NetCDF and put them on our own DODS

Tom,

Here are some rough estimates on the grib2->netCDF file size conversions.
A 5.8 meg grib2 ends up as a 180+ meg netCDF file.  The grib2 has has
multple packing schemes/groups of data inside the file and it can have as many
groups it needs to be efficient. Also grib2 has methods to encode
missing values w/o using any data space. It's actually efficient in
packing the data.  Comparing this to grib1->netCDF, it is usually a 10
fold increase, ie grib1 5 meg end up as 50 meg netCDF.  Just wanted you to know
this as size might be an issue in getting the data on NOAAport, CONDUIT,
etc. THREDDS is working on putting a netCDF API on top of grib1 and grib2
files w/o actually converting them to netCDF.  This is in very early
development stages but it will happen.

Robb...


> servers (or send the original files via the IDD where they can be 'decoded'
> for use).
>
> They still believe that every university has and can use gribtonc and they
> should, therefore, just FTP the NDFD data.  I'm pushing them to use the NOMADS
> model (the one that uses DODS... ;-)
>
> We'll see.
>
> Thanks again for the info...sorry I don't have any other examples for ya...
>
> tom
>
>
> Robb Kambic wrote:
>
> > On Wed, 22 Oct 2003, Unidata Support wrote:
> >
> >
> >>------- Forwarded Message
> >>
> >>
> >>>To: Unidata Support <address@hidden>
> >>>From: Tom Whittaker <address@hidden>
> >>>Subject: GRIB2 to netCDF?
> >>>Organization: UCAR/Unidata
> >>>Keywords: 200310221429.h9METkOb014773
> >>
> >>Is there a GRIB2 to NetCDF converter currently available?
> >
> > Tom,
> >
> > Funny you should ask, that's what I've been working on/off for the last
> > couple of months. So far the the only grib2 files that I have to work with
> > are the NDFD files, those you saw displayed at the Usercomm meeting.  Do
> > you have any others? would like to test the it on other files.  The coding
> > progress is the grib2 files have been decoded, now they Grib2 objects need
> > to be conneected to the java API. I'm estimating a couple weeks to a month
> > depending on the how much time I get to work on it.
> >
> > Robb...
> >
> >
> >
> >
> >>Thanks.
> >>
> >>tom
> >>--
> >>Tom Whittaker (address@hidden)
> >>University of Wisconsin-Madison
> >>Space Science and Engineering Center
> >>Cooperative Institute for Meteorological Satellite Studies
> >>Phone/VoiceMail: 608.262.2759
> >>
> >>
> >>------- End of Forwarded Message
> >>
> >>
> >
> >
> > ===============================================================================
> > Robb Kambic                            Unidata Program Center
> > Software Engineer III                          Univ. Corp for Atmospheric 
> > Research
> > address@hidden                 WWW: http://www.unidata.ucar.edu/
> > ===============================================================================
>
> --
> Tom Whittaker (address@hidden)
> University of Wisconsin-Madison
> Space Science and Engineering Center
> Cooperative Institute for Meteorological Satellite Studies
> Phone/VoiceMail: 608.262.2759
>
>

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