Hi Nan,
It's a terminology issue. The feature type terms were coined for local use under pressure (so much pressure that I even failed to consult the CSML feature type names!) to describe data in one of our data schemas, which doesn't include single instantaneous measurements.
It's the concepts that are the important thing, which we identify by neutral keys. I'm quite happy to use different terms to describe the concepts providing the concept definitions match exactly. The only reason I exposed them was to ensure CF didn't head off into concepts that didn't map. Getting a set of terms for these concepts that are universally agreed would be worthwhile. Bringing our local terms into line with CSML would be an obvious first step, which I'll try and do next week (currently on travel) in conjunction with checking through John Caron's mappings to the proposed CF feature types
Meanwhile if you've any further suggestions for change (or additional observational feature types you'd like to see) let me know and I'll do my best to fall into line.
Cheers, Roy.
________________________________
From: cf-metadata-bounces at cgd.ucar.edu [cf-metadata-bounces at cgd.ucar.edu] On Behalf Of Nan Galbraith [ngalbraith at whoi.edu]
Sent: 20 November 2009 16:26
To: cf-metadata at cgd.ucar.edu
Subject: Re: [CF-metadata] CF point observation Conventions
Thanks, Roy.
There's something not quite symmetrical in this, either - maybe it's
"just" terminology, maybe not.
A time series is conceptually identical to a profile, just "turned on its side"
so time is the single incrementing dimension, instead of depth. The difference
turns out to be important in the proposal mainly because of the way we'd
aggregate profiles vs time series.
A point, in my lexicon, is an atomic unit, a single measurement at a single
x,y,z,t. Is there a "single point" in your feature types? Why assign the term
point to a set of measurements with single x, y, and z and progressing t, as
opposed to a set of measurements with single x, y, t values but varying z?
Cheers -
Nan
Lowry, Roy K wrote:
..
The feature terms we use for observational data in BODC are:
Profile - single set of measurements with single (by assumption) x, y, t values but varying spatial z. An example is a single, fully processed (i.e. binned) CTD cast.
Profile collection - an aggregation of profiles into a single data object. An example is all the CTDs from a section or a cruise.
Profile series - a set of measurements with single x,y a fixed set of spatial z values and progessing t. An example is a single moored ADCP deployment record.
Point - a set of measurements with single x, y, and z and progressing t. Example is a single moored recording current meter record.
Point collection - an aggregation of point features in a single container. Example is all the records from all the current meters on a mooring or deployed on a cruise.
Spectrum series - a set of measurements with single x,y a fixed set of non-spatial z values and progessing t. An example is a power spectrum time series from a wave recorder.
2D-trajectory - a set of measurements with variable x, y, t and a single spatial z. Example is the thermosalinograph record from a cruise.
3D-trajectory - set of measurements with variable x, y, t and a single spatial z. Example is the thermosalinograph record from an AUV mission. It is also applicable to a yo-yo CTD station, mirroring Chris's comments on atmospheric "profiles" with variant x,y.
I think that Nan and most of the observational oceanographic community recognise these concepts and consequently, if a mapping to them to your feature definitions is maintained then it will help keep us on board.
Note that the difference between 'point' and 'point collection' is important to me as on observational data manager, which is a different perspective to an observational data ingestor.
Cheers, Roy.
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*******************************************************
* Nan Galbraith (508) 289-2444 *
* Upper Ocean Processes Group Mail Stop 29 *
* Woods Hole Oceanographic Institution *
* Woods Hole, MA 02543 *
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*******************************************************
* Nan Galbraith (508) 289-2444 *
* Upper Ocean Processes Group Mail Stop 29 *
* Woods Hole Oceanographic Institution *
* Woods Hole, MA 02543 *
*******************************************************
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