Hi Stephan,
My understanding is that the CF point of view would be that if you don't
have a data variable, you can't have auxiliary coordinates.
In my experience, if your file only contains 2D lat and lon, it's
because you want to work with them as data variables, not because
they're coordinates for something absent from the file. (That, or it's
some kind of template or fractional file that you plan to add on to
another file, but in that case I don't expect the file to be meaningful
or conformant on its own.)
Can you say a bit about why any libraries that read the file should
always consider lat & lon to be coordinates? It might work to check the
standard_name or the units, instead of looking for a coordinates attribute.
Cheers,
--Seth
On 10/12/14 1:14 AM, Stephan Hoyer wrote:
> In the process of writing a routine to faithfully serialize data
> according to CF conventions, I have encountered a conundrum.
>
> Suppose I have a would like to save a netCDF file representing a spatial
> grid, with 1D variables "x" and "y" and 2D variables "latitude" and
> "longitude". All of these variables should be considered coordinates by
> any libraries that read the file, and I would like to indicate this in
> the netCDF file.
>
> If there was an additional 2D data variable (e.g., "temperature"), I
> could indicate that latitude and longitude are coordinates by adding
> them to the "coordinates" attribute on the "temperature" variable.
> However, I have no such variable here.
>
> Is there any standard way I can indicate that these variables are
> coordinates if there are no non-coordinates on which to add the
> appropriate attribute? I am considering considering using a global
> "coordinates" attribute but that is definitely outside the CF spec.
>
> Thanks,
> Stephan
>
>
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Received on Mon Oct 13 2014 - 11:52:05 BST
