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[CF-metadata] CF calendars (was: problem with times in PSD dataset)

From: Cecelia DeLuca - NOAA Affiliate <cecelia.deluca>
Date: Mon, 17 Dec 2012 12:56:34 -0700

Cathy,

Of the other options, do you find some (or all) completely unacceptable?
Are some better than others?

- Cecelia

On 12/17/2012 10:59 AM, Cathy Smith (NOAA Affiliate) wrote:
> Cecelia
> I support 1) mostly for backward compatibility. I would also strongly
> encourage but not demand that users change their base dates to after 1800
> when it makes sense to do so.
>
> And, I (again) want to make sure that LTMs and their time values are
> addressed before any decisions are made as to negative times and using
> base dates of 1-1-1 and the issue of what year to use for
> climatologies. LTM dates are a problem when one needs to use a
> calendar based on real dates.
>
> Cathy
>
>
> On 12/12/12 9:04 AM, Cecelia DeLuca - NOAA Affiliate wrote:
>> Hi Steve, Jonathan and all,
>>
>> There are not that many options being discussed.
>>
>> With respect to the default calendar:
>>
>> 1 keep the Julian-Gregorian calendar as default (no change)
>> 2 remove the Julian-Gregorian calendar as default, and have no
>> default calendar (grid analogy)
>> 3 replace the Julian-Gregorian calendar as default with the proleptic
>> Gregorian calendar
>> 4 replace the Julian-Gregorian calendar as default with a strict
>> Gregorian calendar
>>
>> Maybe it makes sense for people to cite (or rank) their preference
>> at this point?
>>
>> There were a couple other proposals, depending on which of above is
>> selected:
>> 5 create a strict Gregorian calendar (optional for 1, 2, 3 and needed
>> for 4)
>> 6 remove the Julian-Gregorian calendar (impossible for 1, optional
>> for 2, 3, 4)
>>
>> Again, maybe worth it to see where people are after the round of
>> discussion?
>>
>> Best,
>> Cecelia
>>
>>
>>
>> On 12/10/2012 12:40 PM, Steve Hankin wrote:
>>> Hi Jonathan,
>>>
>>> I'm not sure if my remarks below conflict with your proposed
>>> resolution. But they do dispute the facts you assert, and these
>>> waters are so muddy that agreeing on the facts seems an important
>>> first step.
>>>
>>> On 12/10/2012 1:21 AM, Jonathan Gregory wrote:
>>>> Dear Jon
>>>>
>>>>> Just to repeat a remark that Steve Hankin made whose implications have not been explored in this discussion: different countries adopted the Gregorian calendar at different times. (Greece didn't adopt it till 1923!) So what is considered a valid Gregorian date varies from country to country (and some of those countries don't even exist any more, or at least the boundaries have changed...)
>>>>> 2. The non-proleptic Gregorian calendar is extremely problematic for historical observations as well as for models (astronomers use the Julian calendar consistently for this reason).
>>>> Yes, that's right. Nonetheless I don't think we can abolish the real-world
>>>> calendar, despite its ambiguities, because*_it's the one we really use!_*
>>>
>>> Are you sure this is true? Evidence seems to suggest that our
>>> community has _no use for the mixed Gregorian/Julian calendar at
>>> all_, except the need to resolve the backwards compatibility mess we
>>> have created for ourselves.
>>>
>>> * In everyday life we use is the modern Gregorian calendar, and
>>> are not concerned with historical calendar changes.
>>> * In numerical climate modeling we use the proleptic Greogorian
>>> calendar. (I'll wager you there is no serious paleo-modeling
>>> done with an 11 day discontinuity in its time axis. )
>>> * What do Renaissance historians use when discussing dates that
>>> are rendered ambiguous by differing timings of the
>>> Julian/Gregorian transition in different locations? Do any of
>>> us know? Does it effect any use of CF that we are aware of?
>>>
>>>> As you say, we should be clearer about what the real-world calendar means, in
>>>> cases where_users really want to use it._
>>>
>>> Who are these users? Where is the user who intersects with our
>>> community and really wants to use the mixed Julian/Gregorian
>>> calendar? The only potential user I can think of would be a
>>> Renaissance historian looking at paleo climate model output. That
>>> hypothetical person would already understand that manual calendar
>>> translations were needed to make sense of precise dates at that time
>>> of history (and would almost surely shrug off an 11 day timing
>>> uncertainty in a paleo climate model outputs in any case).
>>>
>>> As Cecelia said, lets drive a stake through the heart of this
>>> madness ... at least to the maximum degree we can given inescapable
>>> backwards compatibility concerns.
>>>
>>> - Steve
>>>
>>>
>>> _______________________________________________
>>> CF-metadata mailing list
>>> CF-metadata at cgd.ucar.edu
>>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>>
>> --
>> ===================================================================
>> Cecelia DeLuca
>> NESII/CIRES/NOAA Earth System Research Laboratory
>> 325 Broadway, Boulder 80305-337
>> Email:cecelia.deluca at noaa.gov
>> Phone: 303-497-3604
>>
>>
>> _______________________________________________
>> CF-metadata mailing list
>> CF-metadata at cgd.ucar.edu
>> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>
> --
> ----------------------------------------------
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> 303-497-6263
> http://www.esrl.noaa.gov/psd/people/cathy.smith/
>
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> esrl.psd.data at noaa.gov
>
>
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-- 
===================================================================
Cecelia DeLuca
NESII/CIRES/NOAA Earth System Research Laboratory
325 Broadway, Boulder 80305-337
Email: cecelia.deluca at noaa.gov
Phone: 303-497-3604
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