Adding a concurring voice to this sensibility. (But I am open to being told these comments don't reflect sufficient intimacy with CF standard names and practice, I am continuing to learn about it.)
One of the persistent questions about names in general, and CF names in particular, is whether one item can be considered the 'same as' another item. The answer obviously differs according to the purpose.
Although I think CF standard names and standard were developed along the principals of "the name will tell you if the two things are the same", in point of fact for some uses it will inevitably be overly specific for that purpose (when I'm looking to match just medium and property but CF adds methods or location qualifiers, say) and in other cases not specific enough (when some property just isn't required or stored, like the individual instrument ID). I think if I want a deterministic and computable answer to whether two terms represent the same medium and property, something external to the terms themselves is needed (an ontology of the terms, or a table lookup) -- the name itself is not sufficient for automated comparison.
In the case of anomaly, someone more involved in the history and motivation may be better at comparing the new terms to the existing terms and deciding where they should go. But as a 'new' user of CF, and one who wants to use it for observational data, I consider 'anomaly' to be much more general concept (for example, a measurement different than measurements before or after, in the vicinity, or averaged together; but including other concepts also). The existing anomaly definitions are confusing in mty context. So I pose the question as: What is the best way CF can accommodate the more general usage of this term going forward? (Or perhaps more accurately, the more general definition of this term. Maybe we just have to have another term for the concepts I associate with anomaly.)
It is certainly true that while I am a member of the community with dozens, maybe hundreds of term suggestions in mind, there is significant work to (a) convince myself that a term is appropriate for CF, and (b) submit it and see it through. This isn't a complaint about the process, but just agreeing that many community members may not express their needs.
John
At 3:39 PM +0100 4/3/08, Jon Blower wrote:
>Hi Philip and Jonathan,
>
>Just to add my opinion to this before the debate withers. It does
>seem odd to put "anomaly" in the standard name, particularly since
>there are many types of anomaly (from any number of well-known
>climatologies or less well-known ad hoc mean fields). It doesn't seem
>like a good idea to keep pushing new things into the standard name
>(which already seem rather overloaded IMHO).
>
>I don't have time right now to think of a better alternative but I
>would have thought that a separate attribute or modifier would be more
>sensible, avoiding a potentially-huge many-to-many relationship that
>could blow up the standard name table.
>
>Also, what if someone wants to express a new anomaly that isn't in the
>standard name table? If the anomaly is expressed in the standard name
>then they have to go through a procedure to standardize the name
>before they can use it "legally". I bet a lot of people won't bother
>to do this. If there were a more generic way of expressing anomalies
>then they could use this immediately.
>
>> From Jonathan:
>> As you say, very few have so far been needed.
>
>In general, I would be very careful of interpreting community silence
>to mean that there is no community need. This mailing list is
>composed of a statistically-small number of very busy people. I
>shouldn't even be replying to this myself, I have lots of deadlines
>this week... ;-)
>
>Jon
>
>On Thu, Apr 3, 2008 at 3:06 PM, Philip Bentley
><philip.bentley at metoffice.gov.uk> wrote:
>>
>> Hi Jonathan,
> >
>> Interesting to learn that this idea was raised previously. If it again
>> fails to receive any supporting voices then I guess it's a non-starter. No
>> problem: we'll go down the normal standard names route.
>>
>> Regards,
>>
>> Phil
>>
>>
>> Dear Phil
>>
>> > Yet is it not the case that the physical property described by the
>> > 'canonical' name and its associated 'anomaly' name is fundamentally
>> > the same? All that's changed is the use of a different reference datum
>> > (i.e. climatological mean instead of zero).
>> > So rather than create "_anomaly" variants of potentially hundreds of
>> > CF standard names, would an alternative solution be to add the term
>> > "anomaly" to the list of standard name modifiers (cf. Appendix C in CF
>> > spec)? In which case we'd be able to use names such as:
>> > "air_temperature anomaly"
>> > "lwe_precipitation_rate anomaly"
>> > "air_pressure_at_sea_level anomaly"
>> > and so on
>>
>> Following an email thread started by Julian Hill, he and I also thought we
>> would propose exactly this, and I mentioned the proposal at the GO-ESSP
>> meeting
>> in Paris last June. However it wasn't received enthusiastically. It is a bit
>> different in concept from the other standard_name modifiers, which are
>> generally intended for "fields of metadata" - standard errors and so on.
>> The anomaly of a quantity is arguably more of a different quantity
>> altogether;
>> a time-interval, for instance, is a different thing from an absolute time.
>>
>>
>>
>> I agree that in principle any quantity *could* be an anomaly, but in
>> practice
>> are we *actually* going to need anomaly quantities for all of them (or a
>> fraction of them which is nearer 100% than 10%, say)? As you say, very few
>> have
>> so far been needed. Perhaps we should decide on that kind of basis how to
>> deal
>> with it.
>>
>> Other views would be helpful.
>>
>> Best wishes
>>
>> Jonathan
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>>
>>
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>>
>
>
>
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>--------------------------------------------------------------
>Dr Jon Blower Tel: +44 118 378 5213 (direct line)
>Technical Director Tel: +44 118 378 8741 (ESSC)
>Reading e-Science Centre Fax: +44 118 378 6413
>ESSC Email: jdb at mail.nerc-essc.ac.uk
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----------
John Graybeal <mailto:graybeal at mbari.org> -- 831-775-1956
Monterey Bay Aquarium Research Institute
Marine Metadata Initiative: http://marinemetadata.org || Shore Side Data System: http://www.mbari.org/ssds
Received on Thu Apr 03 2008 - 10:46:31 BST
