Dear Steve My argument is this: the standard name is the name of a quantity contained in the variable. Time and longitude are quantities. An ensemble is not a quantity, however. In fact, an ensemble_member is not a quantity either, perhaps, but it would be understood to mean ensemble_member "identifier" in some undefined sense, so it's more like a usual standard name.
However I agree that, in cell_methods, for an omitted ensemble axis, it would be more natural to read "ensemble: mean" than "ensemble_member: mean". We could specifically allow "ensemble" as a keyword with this sense (i.e. to indicate a statistic calculated over the members of an ensemble, when there is no dimension or coordinate for the ensemble), like we allow "area" as a special keyword in cell_methods to stand for the combination of horizontal axes (whatever they are). To do that would require a change to the convention, because it's not just a standard_name. As I said, permitting axis='E' would also be a convention change. If anyone would like to propose these additions in a trac ticket, I'd support it. Best wishes Jonathan On Fri, Nov 15, 2013 at 11:27:59AM -0800, Steve Hankin wrote: > On second though it is all thoroughly ambiguous, whether CF names > its axis standard_names for the collective or for the individual > member. "ensemble" seems immediately clear and short, compared to > "ensemble_member", which seems a bit labored. But I understand your > concern over consistency with "realization". Either choice is fine > with me. > > - Steve > > ============================================ > > On 11/15/2013 11:15 AM, Steve Hankin wrote: > > > >On 11/15/2013 10:30 AM, Jonathan Gregory wrote: > >>Dear Steve et al. > >> > >>>I support the idea that the term "ensemble" be allowed (by whatever > >>>machinery) as an alias for "realization". > >>It'd be fine to have an standard_name alias, I agree, but I > >>think it should be > >>"ensemble_member", not "ensemble". The ensemble is the > >>collection of members > >>(aka realizations). > > > >It feels a bit backwards, doesn't it? By this logic shouldn't the > >standard_name "time" be "snapshot" instead -- named for its > >individual members, rather than for its collective? > > > >"time" "depth", "longitude" and "latitude" axes all represent the > >collection of many individual points. By analogy an "ensemble" > >axis would be the collective of many individual members. It's > >true that, the choice of "realization" as a standard_name took the > >opposite outlook. hmmm ... Are we better off to maintain > >consistency with CF's well known geo-spatial axis standard_names? > >or consistency with "realization"? > > > > - Steve > >> > >>>axis="E" also seems like an appropriate step to maintain consistency > >>>with other well known axis types, given the high likelihood that > >>>ensemble axes will become commonplace in the future. > >>That would require a change to the convention to be proposed on > >>a trac ticket > >>by someone. > >> > >>Best wishes > >> > >>Jonathan _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
