Grib2 geographic subdomain

[Wesley Ebisuzaki]

Pierre,

      Try   wgrib2 -undefine out-box   W:E S:N -grib_out output.grb2
      W,E,S,N are in degrees

This command sets all the points outside the box to undefined.   If you need
disk space, gzip works quite well on output.grb2

          Wesley


Pierre Cassar wrote:
> Hi all,
> I would like to extract a geographic subdomain from a big GRIB2 file,
> what should I use?
>
> - The 'ggrib' utility can use only GRIB1 input files.
>
> - The 'wgrib2' -lola option do not produce a grib output file (only
> bin, text and spread mode).
>
> - Converting the big grib2 file to grib1 with 'cnvgrib' and then using
> 'ggrib' is sloooow.
>
> In fact I have i386 P4 machines running FreeBSD 6 and, as there's no
> 'cnvgrib' binary for FreeBSD, I must use a Linux binary in emulation
> mode (kldload linux).
>
> For example to convert a 260MB grib2 file to grib1 (cnvgrib -g21
> file.grib2 file.grib1) my best FreeBSD machine tooks about *15
> minutes*. That's very frustrating considering that I only need a
> little geographical portion of the big file.
>
> What to do?
> Is there a faster way to convert from grib2 to grib1 in FreeBSD other
> than 'cnvgrib' in emulation mode?
> Is there a way to extract a "slice" from a grib2 file?
>
> Thank you very much.
> Pierre Cassar
>