[Esip-documentation] time_coverage_duration and time_coverage_resolution for climatological data

Tue Mar 20 11:17:49 EDT 2018

John,

Thank you very much for the explanation,  that was very useful. I agree
that these are peripheral use cases and there's some ambiguity, so guidance
from the community is appreciated!

-Ajay

On Fri, Mar 16, 2018 at 12:49 AM, John Graybeal <jbgraybeal at mindspring.com>
wrote:

> Well, there are clearly two time durations related to this data set—one
> describing the duration of the whole set, and the other describing the
> duration of the slice that you’ve taken of the data set. Or, to look at it
> another way, the duration represented by the original data, and the
> duration represented by the calculated data. So I suppose there’s a solid
> argument about ambiguity. (I’m pretty sure we didn’t discuss this
> particular use case, if that helps!)
>
> That said, I’d have to disagree with your science steward on this one. The
> data that is represented clearly represents a time coverage of 10 years,
> and if you use start and end times to convey that, it would be too strange
> for people (and software) to see a duration that is not equal to
> end-minus-start. Time coverage should mean the same thing for all 3
> attributes. (Conversely, if you had used the start and end of the month as
> a time_coverage_start/end, that would be weird, because which year are we
> really talking about?)
>
> If you need to reflect that this is not 10 years of data, that clue
> provided by the fact the time coverage resolution would be 1 month. If your
> whole data set is one point for each month of the year, that means you have
> 12 months of data, which indicates climatology pretty clearly to me. If
> your whole data set is just one point, you could still use 1 month for the
> resolution, to reflect the fact that if you have a second data point it
> would be 1 month away. (Which neatly solves the problem of figuring out how
> big an interval is represented by the one point.)
>
> Note that time_coverage_resolution is the only one of the 4 attributes
> that refers to the _values_ in the data set, as opposed to the data set as
> a whole. So it makes sense to me that 1 month fits for that, but 10Y fits
> for the duration of the set as a whole.
>
> These are metadata specifications not precise data descriptions, so it is
> fair to say that we’re at the edge of what’s realistic for ACDD to
> represent. That said, if a user is searching for data sets that span at
> least X years, they would want you to have used 10Y for your duration.
>
> John
>
>
>
>
> ---------------------------------------
> John Graybeal
> jbgraybeal at mindspring.com
>
>
> On Mar 14, 2018, at 20:22, Ajay Krishnan - NOAA Affiliate via
> Esip-documentation <esip-documentation at lists.esipfed.org> wrote:
>
> Hi Ed,
>
> Thanks for your response but that still won't address the issue. We are
> making use of the time_coverage_start and time_coverage_end attributes (to
> give the user the idea that it is a decadal climatology).
> We've omitted the time_coverage_resolution attribute since there is only
> one time stamp.
>
> Is it better to not include the resolution/duration attributes or any of
> the time_coverage attributes for that matter, for climatological products?
>
> Thanks,
> Ajay
>
> On Tue, Mar 13, 2018 at 3:39 PM, Armstrong, Edward M (398G) <
> Edward.M.Armstrong at jpl.nasa.gov> wrote:
>
>> Hi Ajay,
>>
>>
>>
>> I would suggest you could use this three attributes to described the time
>> series start/stop and time step:
>>
>>
>>
>> time_coverage_start
>>
>> string
>>
>> Describes the time of the first data point in the data set. Use the ISO
>> 8601:2004 date format, preferably the extended format as recommended in the
>> Attributes Content Guidance section.
>>
>> time_coverage_start = "2016-09-01T08:12:01" ;
>>
>> required
>>
>> ACDD 1.3
>>
>> time_coverage_end
>>
>> string
>>
>> Describes the time of the last data point in the data set. Use ISO
>> 8601:2004 date format, preferably the extended format as recommended in the
>> Attributes Content Guidance section.
>>
>> time_coverage_end = "2016-09-01T08:17:59" ;
>>
>> required
>>
>> ACDD 1.3
>>
>> time_coverage_resolution
>>
>> string
>>
>> Describes the targeted time period between each value in the data set.
>> Use ISO 8601:2004 duration format, preferably the extended format as
>> recommended in the Attributes Content Guidance section.
>>
>>  time_coverage_resolution = "00:05:58";
>>
>> recommended
>>
>> ACDD 1.3
>>
>>
>>
>> From:
>>
>> https://podaac.jpl.nasa.gov/PO.DAAC_DataManagementPractices
>>
>> *From: *Esip-documentation <esip-documentation-bounces at lists.esipfed.org>
>> on behalf of Ajay Krishnan - NOAA Affiliate via Esip-documentation <
>> esip-documentation at lists.esipfed.org>
>> *Reply-To: *Ajay Krishnan - NOAA Affiliate <ajay.krishnan at noaa.gov>
>> *Date: *Tuesday, March 13, 2018 at 10:12 AM
>> *To: *"<esip-documentation at lists.esipfed.org>" <
>> esip-documentation at lists.esipfed.org>
>> *Subject: *[Esip-documentation] time_coverage_duration and
>> time_coverage_resolution for climatological data
>>
>>
>>
>> Hello All,
>>
>>
>> I am looking at populating global attributes for a dataset which contains
>> monthly mean temperature for 1995-2004.
>>
>>
>>
>> I had recommended
>>
>> :time_coverage_duration="P10Y" ;
>>
>> The science steward is not convinced, and perhaps rightly so, because it
>> is not a 10yr field but a 1 month field which is a mean of 10yrs of that
>> month. How should the global attribute be populated in this case?
>>
>> What about the time_coverage_resolution attribute?
>>
>>
>>
>> Are such complicated cases outside the purview of ACDD?
>>
>>
>>
>> Thanks!
>>
>> --
>>
>> *Ajay Krishnan*
>>
>> Geospatial Data Developer | Science & Technology Corporation <http://stcnet.com/> - Federal Government Contractor
>> NOAA National Centers for Environmental Information (NCEI)
>>
>> SSMC3 - 1315 East West Hwy Silver Spring MD 20910 <https://goo.gl/maps/ovow9dP4nhE2>
>> ajay.krishnan at noaa.gov
>>
>> Phone: 301-713-4864 <(301)%20713-4864>
>>
>> Customer Support:  1-301-713-3277 or ncei.info at noaa.gov
>>
>>
>>
>>
>
>
> --
>
> *Ajay Krishnan*
> Geospatial Data Developer | Science & Technology Corporation <http://stcnet.com/> - Federal Government Contractor
> NOAA National Centers for Environmental Information (NCEI)
> SSMC3 - 1315 East West Hwy Silver Spring MD 20910 <https://goo.gl/maps/ovow9dP4nhE2>
> ajay.krishnan at noaa.gov
> Phone: 301-713-4864 <(301)%20713-4864>
> Customer Support:  1-301-713-3277 or ncei.info at noaa.gov
>
> _______________________________________________
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>
>
>

-- 

*Ajay Krishnan*
Geospatial Data Developer | Science & Technology Corporation
<http://stcnet.com/> - Federal Government Contractor
NOAA National Centers for Environmental Information (NCEI)
SSMC3 - 1315 East West Hwy Silver Spring MD 20910
<https://goo.gl/maps/ovow9dP4nhE2>
ajay.krishnan at noaa.gov
Phone: 301-713-4864 <(301)%20713-4864>
Customer Support:  1-301-713-3277 or ncei.info at noaa.gov
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