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Re: 20020820: NetCDF data files

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  • Subject: Re: 20020820: NetCDF data files
  • Date: Tue, 20 Aug 2002 14:11:02 -0600
>To: "'address@hidden'" <address@hidden>
>From: "Bui, Them" <address@hidden>
>Subject: NetCDF data files
>Organization: NASA Marshall Space Flight Center
>Keywords: 200208201438.g7KEcFK11508

Hi Them,

> I download some compressed binary NetCDF data files. These files with a
> ".gz" file extension were compressed using gzip which is the GNU compression
> utility. I decompressed with WinZip on a PC and these files are now
> decompressed with a ".L1B" and it is not in the text or readable format.
> Could you help us with the information and/or how to display these file or
> create a trip image?

WinZip can uncompress gzipped files OK, but are you sure the original
uncompressed files were netCDF?  Typically, netCDF files have a ".nc"
extension.  NetCDF files are binary data files, so you should not
expect to be able to interpret them as text.  You can tell if your
".L1B" file is a netCDF file and also see what is in it by invoking
the "ncdump" utility on it, and if it it a netCDF file, it will output
an ASCII version to standard output.

  $ ncdump t3.nc
  netcdf t3 {
  dimensions:
          time = UNLIMITED ; // (50 currently)
          d2 = 2 ;
  variables:
          short array1(time, d2) ;
          short array2(time, d2) ;
          short array3(time, d2) ;
          short array4(time, d2) ;
  data:
    ...
  }

On the other hand, if it's not a netCDF file, it will output a
message:

  $ ncdump stuff.exe
  ncdump: stuff.exe: Not a netCDF file

The ".L1B" extension makes me wonder if the uncompressed file isn't
really level 1B polar orbiter or MODIS data in some other format (CDF?
HDF-EOS?).

If the file is really netCDF and you need other utilities than ncdump
to interpret or visualize the data, see the web page:

  http://www.unidata.ucar.edu/packages/netcdf/software.html

for software for manipulating or displaying netCDF data.

--Russ

_____________________________________________________________________

Russ Rew                                         UCAR Unidata Program
address@hidden                     http://www.unidata.ucar.edu