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Re: 20031106:necessary netcdf attributes

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  • Subject: Re: 20031106:necessary netcdf attributes
  • Date: Thu, 06 Nov 2003 14:18:10 -0700
>To: address@hidden
>From: Danika Gilbert <address@hidden>
>Subject: necessary netcdf attributes?
>Organization: UCAR/Unidata
>Keywords: 200311052130.hA5LUgOb019682

Hi Danika,

> I've run into a problem with some netcdf files we've created.  The problem
> is that I crash ncPlot or ncBrowse when I try to look at some fields we've
> created and written out to existing netcdf files.
> 
> Actually, what we've done is copy .nc files and add new fields to the end
> of these files.  I don't have this problem when I plot any of the fields
> that were present in the original .nc files.
> 
> The only difference I can clearly tell is that we have not included any
> variable attributes for our new fields.  Are there any of these attribute
> fields that are essential for plotting in ncPlot, ncBrowse or other netcdf
> plotting tools?
> 
> When I do an ncdump -v on our new variables, the data displays fine.  I
> can also plot the data fine if I load the .nc files into matlab.
> 
> Any suggestions/thoughts?

Looking at the ncPlot User's Guide, it says the data must conform to
the NCAR-RAF/nimbus conventions:

  http://raf.atd.ucar.edu/Software/netCDF.html

which says 

  All variables contain the basic attributes units, long_name, and
  _FillValue (pre 1998 spelled MissingValue). ....

and then lists some additional variable attributes.  I don't know
whether omitting units, long_name, or _FillValue would cause ncPlot to
crash, but it might.  I suggest you contact the ncPlot developer
(Chris Webster?).

The ncBrowse site at PMEL seems to be down right now so I can't check
it, but it was my understanding from the developer, Don Denbo, that
ncBrowse is supposed to work on arbitrary netCDF files, although it
can take advantage of EPIC and COARDS conventions; it should not
require variable attributes.  If the latest version of ncBrowse fails
on one of your netCDF files, I'm sure Don would want to hear about it
and provide a workaround or fix.

--Russ

_____________________________________________________________________

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