I think #1 is a great idea as it has been a practice in a number of satellite missions.
#2 I am not too fond of. Best practice says that when offset is not specified implicitly GMT must be assumed. So I think specifying a ?Z? in ISO time stamp is only necessary when specifying a non zero offset.
From: CF-metadata <cf-metadata-bounces at cgd.ucar.edu<mailto:cf-metadata-bounces at cgd.ucar.edu>> on behalf of Chris Barker <chris.barker at noaa.gov<mailto:chris.barker at noaa.gov>>
Date: Thursday, September 22, 2016 at 8:45 AM
To: Jonathan Gregory <j.m.gregory at reading.ac.uk<mailto:j.m.gregory at reading.ac.uk>>
Cc: "cf-metadata at cgd.ucar.edu<mailto:cf-metadata at cgd.ucar.edu>" <cf-metadata at cgd.ucar.edu<mailto:cf-metadata at cgd.ucar.edu>>
Subject: Re: [CF-metadata] Temporal nitpicks. Was: CF-metadata Digest, Vol 161, Issue 3
On Thu, Sep 22, 2016 at 5:53 AM, Jonathan Gregory <j.m.gregory at reading.ac.uk<mailto:j.m.gregory at reading.ac.uk>> wrote:
Dear Chris et al.
I may have missed it - are you proposing a change or a clarification to the
text of the CF standard document?
yes and no:
Yes, in that I'm proposing that somthing be chaged in the docuemnt -- really about recommendations and example,s rather than chanign anything about what it allowed.
No, in that I (or anyone else) has not proposed any particular text.
But if there seems to be a consensus that it would be good ti updated the docs to make these recommendaiont,s than hopefully someone will suggest actual text. (I'm short of roundtoits at the moment).
I think these are the ideas:
1) recommend ISO-8601 compliant time strings
2) recommend that an offset (or 'Z') always be provided in a time string.
3) Have all examples conform to the above.
Does anyone this these are NOT good ideas?
NOTE: as I understand it, ISO-8601 time strings are acceptable to UDUnits, and thus this would not be a change to the standard in any way -- simply recommendations of good practice.
TBD: According to wikipedia, ISO requires a "T" in between teh date and time, but then says " It is permitted to omit the 'T' character by mutual agreement" so do we want to recommend one or the other? I think UDUnits does not use a T but maybe it will accept it. (the Python netcdf4 lib added support for the optional "T" a couple years ago -- no idea about any other parsing libs.
-CHB
Best wishes and thanks
Jonathan
----- Forwarded message from Chris Barker <chris.barker at noaa.gov<mailto:chris.barker at noaa.gov>> -----
> Date: Wed, 21 Sep 2016 12:52:48 -0700
> From: Chris Barker <chris.barker at noaa.gov<mailto:chris.barker at noaa.gov>>
> To: Nan Galbraith <ngalbraith at whoi.edu<mailto:ngalbraith at whoi.edu>>
> CC: "cf-metadata at cgd.ucar.edu<mailto:cf-metadata at cgd.ucar.edu>" <cf-metadata at cgd.ucar.edu<mailto:cf-metadata at cgd.ucar.edu>>
> Subject: Re: [CF-metadata] Temporal nitpicks. Was: CF-metadata Digest, Vol
> 161, Issue 3
>
> On Tue, Sep 20, 2016 at 5:45 AM, Nan Galbraith <ngalbraith at whoi.edu<mailto:ngalbraith at whoi.edu>> wrote:
>
> > Can we recommend the use of ISO-compatible date strings, with
> > the caveat that time zone should always be included?
> >
>
> Yes, we really should do that (though it's an offset that is specified, not
> a time zone)
>
> It's unfortunate that ISO defaults to local time, and that seems to be
> > non-negotiable.
> >
>
> yup :-(
>
> This is what we use in the OceanSITES implementation of CF. Obviously,
> > it won't solve everyone's needs,
>
>
> I'm trying to see whos needs it wouldn't suit folks may well want local
> time, rather than UTC, but having it be unspecified does no one any good.
>
> and specifying times in "true" local time, with DST baked in is simply a
> nightmare for everyone --- it really, really should be discouraged!
>
> -CHB
>
>
> --
>
> Christopher Barker, Ph.D.
> Oceanographer
>
> Emergency Response Division
> NOAA/NOS/OR&R (206) 526-6959<tel:%28206%29%20526-6959> voice
> 7600 Sand Point Way NE (206) 526-6329<tel:%28206%29%20526-6329> fax
> Seattle, WA 98115 (206) 526-6317<tel:%28206%29%20526-6317> main reception
>
> Chris.Barker at noaa.gov<mailto:Chris.Barker at noaa.gov>
> _______________________________________________
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Emergency Response Division
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