Sorry, I don't understand why you simply label your datasets
calendar: proleptic_gregorian
if they go before 1582, and support gregorian with the restriction
that the values correspond
to post 1582. Much better than changing the calendar attribute
standard (again!), and messing up existing code that does support the
standard, and existing data that is correctly labeled with the current
standard.
Benno
On Wed, Oct 13, 2010 at 8:55 PM, Earl Schwab <eschwab.esmf at gmail.com> wrote:
>
> Hi,
>
> As Tony indicated, the ESMF Team also supports this proposal to make
> the CF default/standard Gregorian calendar proleptic. Like CCSM, our
> Gregorian calendar is proleptic, and, also like CCSM, we do not
> support a mixed Julian/Gregorian historical calendar, as we've had
> no such requirement to-date from our users.
>
> Regards,
> Earl Schwab
> ESMF Core Team
>
>
> -------- Original Message --------
> Subject: proposed change to calendar definitions
> Date: Fri, 08 Oct 2010 11:00:57 -0700
> From: Tony Craig <tcraig at ucar.edu>
> To: cf-metadata at cgd.ucar.edu
> CC: Mariana Vertenstein <mvertens at ucar.edu>, eschwab.esmf at gmail.com
>
> The NCAR CCSM climate model tries to follow the CF standard
> as much as possible with regard to input and output datasets.
> However, we are finding it nearly impossible to adhere to the
> calendaring standard. We do not have access to time managers
> either internally or through external sources, such as ESMF, to
> support the default CF "gregorian/standard" calendar as documented here,
>
> http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.4/cf-conventions.html#calendar
>
> And at the end of that section, the CF convention notes in particular
> the challenges associated with "the discontinuity" in the mixed
> gregorian/julian calendar. We have discussed calendaring issues with the
> ESMF developers, and they also have no immediate plans to support
> the mixed gregorian/julian calendar. ESMF is one of our primary tools
> for supporting infrastructure in climate models, especially time managers.
>
> As a result, in our implementation, we treat the calendar naming
> conventions differently.
>
> gregorian == proleptic_gregorian
>
> and mixed gregorian/julian is not supported.
>
> We would like to propose a change to the CF calendar conventions to
> reflect what we believe the community is already doing. We propose
>
> 1. continued support of the name proleptic_calendar for backwards
> compatability.
> 2. changing the definition of gregorian and standard to be the proleptic
> gregorian calendar instead of the mixed gregorian/julian.
> 3. make the proleptic gregorian the default calendar
> 4. add a new calendar name, such a gregorian_julian to provide the
> ability to define a mixed calendar in CF conventions.
>
> that would change the definition in the above CF standards document to the
> following
>
> gregorian or proleptic_gregorian or standard
> A gregorian calendar extended to dates before 1582...
> This is the default.
>
> gregorian_julian
> Mixed Gregorian/Julian calendar as defined by Udunits.
>
> We've had discussions about this with ESMF and they are supportive
> of this proposal. Their gregorian calendar is also proleptic and this
> proposed change would make both their and our implementation more
> closely aligned with the CF convention.
>
> If you have any questions, please feel free to contact me. thanks,
>
> tony..........
>
>
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>
--
Dr. M. Benno Blumenthal? ? ? ? ? benno at iri.columbia.edu
International Research Institute for climate and society
The Earth Institute at Columbia University
Lamont Campus, Palisades NY 10964-8000?? (845) 680-4450
Received on Fri Oct 15 2010 - 09:58:48 BST
