Hi Cathy:
I think that you are using "backwards compatible" in a different way.
The current proposal(s) would not change files that are written with
:Conventions="CF-1.x", where x <= 6. Files with x > 6 could still use
the (ill-advised) old way if they want to, by putting an explicit
calendar attribute in. But if theres no explicit calendar attribute,
then these new files will be interpreted in a way that is less likely to
give incorrect dates.
So, im not sure why you keep saying "shouldn't break current files",
since there is no such proposal on the table.
John
On 12/17/2012 4:13 PM, Cathy Smith (NOAA Affiliate) wrote:
> Cecelia
>
> I think a solution shouldn't break current files which followed what had
> been a standard for a long time (however ill-advised the standard was).
> I don't have a good sense of what might break if the standard changed in
> terms of software so I can' speak for all users but I do know many
> people have downloaded our mean files with 1-1-1 base dates (ignoring
> the climatologies for now). While we can potentially change what we have
> either by changing the dates and/or adding a calendar attribute,
> changing the default calendar may create errors in reading dates for
> users who already have those files (which are currently CF complaint ).
> And, they won't have the same ability to change the files and they
> wouldn't necessarily know they needed to. I think no default at all
> would be problematic as what would software do? So, I would support the
> inclusion of a calendar attribute that would be used by software if
> there but using the old default calendar if not. Also, I would support
> making a calendar attribute for new files mandatory (with an updated CF
> version) but I would keep backwards compatibility unless it were
> reliably shown it was not an issue with users.
> I'm not convinced that the users needs (as opposed to developers) have
> been adequately researched.
>
> Cathy
>
>
>
> On 12/17/12 12:56 PM, Cecelia DeLuca - NOAA Affiliate wrote:
>> 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
>>>
>>> --
>>> ----------------------------------------------
>>> NOAA/ESRL PSD and CIRES CDC
>>> 303-497-6263
>>> http://www.esrl.noaa.gov/psd/people/cathy.smith/
>>>
>>> Emails about data/webpages may get quicker responses from emailing
>>> 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
>
> --
> ----------------------------------------------
> NOAA/ESRL PSD and CIRES CDC
> 303-497-6263
> http://www.esrl.noaa.gov/psd/people/cathy.smith/
>
> Emails about data/webpages may get quicker responses from emailing
> esrl.psd.data at noaa.gov
>
>
>
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Received on Mon Dec 17 2012 - 17:57:52 GMT
