Hi Jonathan,
I do think that it would be right to deprecate the use of the mixed Julian-
Gregorian calendar for all cases except where there is really a need for time
coordinates before the change of calendar. There may be no such cases (as I
agree in my previous posting, to Steve) but we cannot be sure and I would
guess it might occasionally be needed.
I've probably said all this before, but to summarise, my first choice would
be to change the default to be strict Gregorian from 1582, which excludes the
worst problem, but if others argue that there is need to prevent confusion
between real-world and model calendars for reference dates more recent than
1582, I would accept my second choice, which is not to allow a default at all.
That's my second choice because I think it would cause annoyance for many
people who've been used to coding COARDS-like real-world time coordinates
without defining their calendar, whose datasets might become illegal, either
because their software is upgraded to use the new version of CF in which this
change is made, or because their software changes its default behaviour without
paying attention to the Conventions attribute, as Chris also mentions.
Please consider me on board with the solution you've proposed. You,
John, Steve, Cathy and others are in a better position than I am to
judge the impacts of such a change on data set users. I'm disappointed
that the solution is still a bit of a snub for modelers, but in practice
it probably doesn't matter much.
I do wonder about deprecation of the current default and the
recommendation to specify calendars, and whether those behaviors are
well-defined. For example, is a time period defined after which the
current default is not supported at all? And is it codified that
recommendations should generate warnings in tools if they are not
followed? (I assume the mixed calendar itself would not be deprecated,
just its use as the default?)
Best,
Cecelia
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--
===================================================================
Cecelia DeLuca
NESII/CIRES/NOAA Earth System Research Laboratory
325 Broadway, Boulder 80305-337
Email: [email protected]
Phone: 303-497-3604
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