[CF-metadata] ensemble dimension

From: Jonathan Gregory <j.m.gregory>
Date: Tue, 16 Mar 2010 17:22:09 +0000

Dear John

> Im not sure if we ever converged on how to write ensemble files.
No, we didn't. If I remember correctly, we couldn't agree on the relationship
between attributes and coordinates, and that was a sticking-point. I thought
that we ought to allow multivalued auxiliary coord variables for ensemble
axes, corresponding to attributes that might be used to describe a single
model. I would give these standard_names to identify them. Paco started the
discussion, and in the end he made his own decisions for what to do for the
ENSEMBLES project (because CF had not concluded), so he might comment on it.

> Particularly, how does software recognize the ensemble dimension?
We didn't agree. But at the end of the discussion, Steve also suggested that
it could be identified by an axis attribute, just as you have. I like that
idea too. But it could also be given a standard name, like other coordinate
variables e.g. ensemble_member_identifier. I suppose the values of this
coord var might be either numeric or strings, though it your example it is
integer. I haven't looked at the trac ticket to see if we discussed these
points before.

> Perhaps we should add :axis = "Ensemble" to the model coordinate variable?
I'd suggest lower case, like most CF keywords. The other axis attributes are
all single letters (X Y Z T) but I don't think it would be a problem to use
a word.

Best wishes

Jonathan
Received on Tue Mar 16 2010 - 11:22:09 GMT