[CF-metadata] the need to store lat/lon coordinates in a CF-compliant netCDF file

From: Jonathan Gregory <j.m.gregory>
Date: Thu, 4 Aug 2011 08:23:08 +0100

Dear all

I agree with Balaji about this:
> It is perfectly possible to configure a GCM out of components with
> inconsistent datums.
...
> I still feel my principal objection to specifying the datum is the
> implication of precision that does not exist.
This kind of argument may apply more to models, but it appears from the
comments that it might apply to obs datasets as well, for instance when they
have been assembled from various sources, which could be poorly documented.

Hence in terms of John's questions, I think this is good:

> 1) possible recommendations by CF to always include the datum, and
> making sure we have the right metadata to do so.

We could make a recommendation in the standard document to include the
grid_mapping, if there is an applicable one, whenever there are horizontal
coordinates. The CF checker would then produce a warning if the grid_mapping
was absent. But I don't think it is the role of CF to include:

> 2) possible recommendations by CF as to what to do if the datum is not
> present, or is only partially specified.

CF is a convention for allowing metadata to be provided. Its purpose is not
to prescribe or guess what the metadata should be. There is lots of important
metadata which is optional, such as standard names and bounds, and we do not
recommend what should be done when they are missing.

Cheers

Jonathan
Received on Thu Aug 04 2011 - 01:23:08 BST