Hi Karl,
I think that the existing spec can't accurately represent your climatology.
The spec implicitly assumes that all the subintervals start and end at
the same point in the annual cycle, and that therefore we can represent
both the start and end of the input data and the start and end of the
subinterval using just two dates, the start and end of the first and
last subintervals, because they are representative.
DJF data that starts in Jan of the first year and ends in Dec of the
last year violates the assumption that the two sets of boundaries align,
so I think there's straight-up no way to be accurate and follow the spec
as it's currently written.
I think it would make sense to do it by having BOTH a bounds variable
(2000-12-01 to 2011-01-01) AND a climatology variable (1999-12-01 to
2010-03-01). The bounds variable would indicate the actual start and
end of the input data, while the climatology variable would indicate the
nominal start and end of the data being represented (i.e, winter 2000
through winter 2010, inclusive.)
However, the second paragraph of section 7.4 says "a climatological time
coordinate variable does not have a bounds attribute. Instead, it has a
climatology attribute...", so that's not strictly legal by CF-1.6.
Perhaps we should propose a ticket to make it optional to have a bounds
attribute in addition to the climatology attribute, if the start and end
of the input data don't align with the subinterval boundaries?
Cheers,
Seth
On 2/11/16 11:25 AM, Karl Taylor wrote:
> Hi Jim,
>
> I considered that, but doesn't that indicate to someone who isn't
> already aware of the actual time-period covered that data was used
> starting 2000-12-01 and ending in 2010-03-01, even though data from the
> months 2000-01 and 2000-02 and 2010-12 also were included in computing
> the climatologies?
>
> best regards,
> Karl
>
> On 2/11/16 10:15 AM, Jim Biard wrote:
>> Karl,
>>
>> I think you should be able to handle this in the bounds variable. If
>> you write the first entry as "2000-12-1", "2010-03-01", doesn't that
>> describe things correctly?
>>
>> Grace and peace,
>>
>> Jim
>>
>> On 2/10/16 6:37 PM, Karl Taylor wrote:
>>> Dear CF community,
>>>
>>> In representing the seasonal climatology based on data available for
>>> the period January 1, 2000 through December 31 2010, what would be
>>> the correct climatology_bounds?
>>>
>>> climatology_bounds = "1999-12-1", "2011-3-1",
>>> "2000-3-1", "2010-6-1",
>>> "2000-6-1", "2010-9-1",
>>> "2000-9-1", "2010-12-1" ????
>>>
>>> I would note that this seems to capture the idea that we are
>>> reporting seasonal means, but it also seems to indicate that this is
>>> based in part on data from Dec. 1999 and Jan.-Feb. 2011, when it
>>> isn't. Is this the best I can do? [Of course the convention can
>>> never tell us if data are complete in forming a climatology. If 1
>>> year were missing, this would not affect the attributes.]
>>>
>>> I suppose the in the cell_methods attribute ("time: mean over days
>>> time: mean over years" I could add non-standardized information (as
>>> permitted by CF), for example: "time: mean over days time: mean
>>> over years (with data from the period 2000-1-1 to 2011-1-1)"
>>>
>>> thanks for any suggestions,
>>> Karl
>>>
>>>
>>>
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>>
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Received on Thu Feb 11 2016 - 12:04:22 GMT
