Dear Steve Sorry not to be clear.
> Mine would be this: We add "ensemble" as a standard_name. Then > normal CF guidelines support its use in cell_methods, as in > "ensemble: mean". Doing so also restores compatibility with CDM -- > an issue that effects real-world interoperability. It seems a clean > and simple solution. That is not my conclusion. I do not think "ensemble" makes sense as a standard name. An synonym for "realization" is something with the sense of "ensemble member". "Ensemble" means all the members together. I don't think it would be meaningful to have a variable with "ensemble" as a standard name. The existing conventions and standard_name table allow us to put e.g. "realization: mean" in cell_methods to indicate a mean over the members of an ensemble, in the case where there is no dimension named "realization". In that case, the name "realization" is interpreted as a standard name, and the cell_methods entry implies that the mean has been calculated over all the members of an unspecified ensemble. I feel that this convention is OK and probably adequate. However you and others have suggested, I think, that it is not clear enough. Therefore my conclusion is that we could (if you think it worthwhile) define "ensemble:" as a special keyword that could be used in cell_methods to indicate that the statistic has been calculated over the members of an unspecified ensemble. That would be defined to mean exactly the same as "realization:" in the sense of the last paragraph, but might be clearer. Best wishes Jonathan > > >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 > ----- End forwarded message ----- _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
