[Go-essp-tech] DRS corrections and extensions

Thu Jun 7 06:18:14 MDT 2012

Hello Karl,

Apologies for missing your earlier email.

(1) Like Stephen, I'm concerned about the complexity of the "XXXX" section. My first suggestion would be to drop the first hyphen and "lat" and "lon", changing "g-lat20S20Nlon170p5W130p5W" to "g20S20N170p5W130p5W". I'd also be tempted to drop the "p5" terms: for some grids (e.g. Gaussian) the exact limits will have many decimal places and so there will need to be some specification of the level of truncation expected, and I think the most convenient would be to round to the nearest integer.

(2) To make parsing of the overall file name easier, you could use c1_c2_..... [_<time range>][.<spatial info>].nc - using a "." Instead of "_" makes life easier for file parsers. Technically this is not necessary, as the "g" already makes it unambiguous, but parsers have to deal with the special case of gridspec files and adding more variants make life more complicated. Using "." will make it easier to separate the parsing of the existing components from the new ones.

(3) As Stephen points out, in the present form, in a string "g-aaa-bbb" the term "aaa" could be either a region from an gazetteer or a designation of a type of surface ("ocn" or "lnd"). Having to look through multiple vocabularies is a problem for file name interpretation, even if one of them only has two elements. To get over this, I'd suggest something like: ".....[_<time range>][.gXXXX_pYYY-ZZZ].nc", where the "gXXXX" and "pYYY-ZZZ" terms are both optional and the underscore is only present if both are present. This approach will only work if you accept the use of "." suggested in (2) to make a clear break between the first part of the name and the new. This would give us a first section of the file name in which components are identified by position and a 2nd section in which components are identified by the first letter of the component.

Regards,
Martin

From: Karl Taylor [mailto:taylor13 at llnl.gov]
Sent: 06 June 2012 21:58
To: Kettleborough, Jamie; V. Balaji; Steve Hankin; Juckes, Martin (STFC,RAL,RALSP); Lawrence, Bryan (STFC,RAL,RALSP); Pascoe, Stephen (STFC,RAL,RALSP); go-essp-tech at ucar.edu
Subject: Re: [Go-essp-tech] DRS corrections and extensions

Dear all,

In February I asked for comments on my proposal to extend the DRS to  include information about spatio-temporal subsets or means.  I heard from Jamie, but no one else.  I respond to Jamie below, but I also would like your input specifically about:

1.  Is this method of describing spatio-temporal subsets acceptable?
2.  Is it worth taking this step if we don't say anything about other "processed" output?   For example how to describe "regridded" data or multi-model means.

I've attached the proposed version of the DRS, which differs from the one I sent in January only in a couple mods made in response to Jamie.

Best regards,
Karl

On 2/13/12 6:47 AM, Kettleborough, Jamie wrote:
Hello Karl,

this will be terse as I have time to review, but not to necessarily get the words right - hope I don't say anything too bad because of this.

1. section 2.3,  Not sure 'output' should be mentioned under 'product'.  I don't think 'output' ever makes it to publication level, so does not need to appear in a publication level id.  I know cmor produces it, but I think that's kind of historical isn't it, rather than necessary?  Maybe its too late for details like this?
It's true that in the end the CMIP5 output should not remain as "output", but be assigned to "output1" or "output2".  Nevertheless, I don't think there is any harm in keeping it in the DRS.

2. section 2.3 version number: to be consistent with what we really have in CMIP5 I think you need to note that v1, v2 are also present, though any *new* versions should use vYYYYMMDD.
I have modified the text to indicate that software cannot rely on the version number reflecting a date.

3. section 2.3 version:  I wonder if you need to say more (maybe not here, but if not where?) about what triggers a new version.  I think its
  a. anything that changes the content of a file already published and
  b. the addition or deletion of files from any publication data set.
  Pure 'data management' meta data changes (addition of checksums, move to new URL's) need not trigger a new version.
  Do you also need to say there is no guarantee that old versions will be kept (unless they have a DOI).
I've added some of this information now to the document.

4. section 2.4 Temporal Subsets or means: I don't understand the 'avg' example, or if I do I don't know if its right (but the point is relatively minor).  I think the example you quote as one 6 month mean field in it.  This is based on 1 day means.  I think its a little anomalous to keep the frequency as 'day' in this case.  That's not quite consistent with the definition (and I think all other uses) of frequency.  Strictly speaking frequency should be 6mon no?  (I may have misunderstood).
I think you're right.  I'm not sure why I thought this was the right way to do it.  I've changed the example,

5. section 3.5.  Does this need clarifying? I think the current wording is potentially confusing,  I think it should say something like:

'URLs referencing the data files will have a site dependent prefix (that may change due to site-specific data management tasks) followed by the directory structure.  This directory structure should (but may not) follow the recommendations of section 3.3'

I've modified the text as suggested.

6. I've noticed that the thredds catalogs also expose a thing called the file_id, e.g

<property name="file_id" value="cmip5.output1.CNRM-CERFACS.CNRM-CM5.rcp45.mon.ocean.Omon.r1i1p1.vo_Omon_CNRM-CM5_rcp45_r1i1p1_203601-204512.nc"/>

I don't know if they need a mention as being anything important (we don't use them as they don't give any version info).

We've already given 5 use cases, which I think is enough.  The DRS is used in a number of other ways.

Hope this is useful,
Yes thanks very much!
Karl

Jamie

________________________________
From: go-essp-tech-bounces at ucar.edu<mailto:go-essp-tech-bounces at ucar.edu> [mailto:go-essp-tech-bounces at ucar.edu] On Behalf Of Karl Taylor
Sent: 10 February 2012 01:32
To: V. Balaji; Steve Hankin; Martin Juckes; Bryan Lawrence; Stephen Pascoe; go-essp-tech at ucar.edu<mailto:go-essp-tech at ucar.edu>
Subject: [Go-essp-tech] DRS corrections and extensions
Dear all,

Attached is my attempt to make the DRS consistent with CMIP5 (in describing the precision of "time instants"), but primarily to extend it to a more complete treatment of spatio-temporal subsets or means.  I've also corrected a few typos.

Comments most welcome.  In particular could someone recheck sections 3.3-3.5 (which haven't been changed by me) to see if they remain consistent with CMIP5?

thanks and best regards,
Karl

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