Hi.
By the way, I found a nice page that I hadn't seen before that talks
about GPS vs UTC, etc.
http://www.oc.nps.edu/oc2902w/gps/timsys.html
Grace and peace,
Jim
On 6/29/15 12:21 PM, Jonathan Gregory wrote:
> Dear Tim and Nan
>
> If I have understood correctly, I think your two emails suggest that we do need
> a distinction of the precise and imprecise cases. As usual, I believe that CF
> should not prescribe to users what they should do; its aim is to allow them to
> describe what they have done. Different levels of precision are needed for
> different datasets.
>
> Following the emails that Jim and I exchanged, we could distinguish:
>
> gregorian: Real world-times, but without specifying whether UTC or GPS
> timestamps are intended, nor whether the encoding was done with or without leap
> seconds. The decoded times could differ by several seconds from UTC. I think
> this is Nan's use-case.
>
> gregorian_nls: UTC timestamps were encoded without leap seconds, with a
> reference UTC timestamp. I think this is Tim's use-case. This is not accurate
> according to UTC but it can be decoded precisely as intended. Jim points out
> that it's not a real-world calendar, but it's not far off.
>
> Have I correctly described these as your cases?
>
> In addition, we propose two other calendars:
>
> gregorian_utc: The encoded and reference timestamps are UTC, and the encoding
> is done with leap seconds allowed for. Hence the time coord is an accurate
> elapsed time.
>
> gregorian_gps: The encoded and reference timestamps are GPS, and the encoding
> is done without leap seconds. Again, the time coord is accurately elapsed time.
> I think this is the use-case which originally started this thread!
>
> Best wishes
>
> Jonathan
> _______________________________________________
> CF-metadata mailing list
> CF-metadata at cgd.ucar.edu
> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
--
CICS-NC <http://www.cicsnc.org/> Visit us on
Facebook <http://www.facebook.com/cicsnc> *Jim Biard*
*Research Scholar*
Cooperative Institute for Climate and Satellites NC <http://cicsnc.org/>
North Carolina State University <http://ncsu.edu/>
NOAA National Centers for Environmental Information <http://ncdc.noaa.gov/>
/formerly NOAA?s National Climatic Data Center/
151 Patton Ave, Asheville, NC 28801
e: jbiard at cicsnc.org <mailto:jbiard at cicsnc.org>
o: +1 828 271 4900
/Connect with us on Facebook for climate
<https://www.facebook.com/NOAANCEIclimate> and ocean and geophysics
<https://www.facebook.com/NOAANCEIoceangeo> information, and follow us
on Twitter at _at_NOAANCEIclimate <https://twitter.com/NOAANCEIclimate> and
_at_NOAANCEIocngeo <https://twitter.com/NOAANCEIocngeo>. /
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.cgd.ucar.edu/pipermail/cf-metadata/attachments/20150629/4efafade/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: CicsLogoTiny.png
Type: image/png
Size: 15784 bytes
Desc: not available
URL: <http://mailman.cgd.ucar.edu/pipermail/cf-metadata/attachments/20150629/4efafade/attachment-0001.png>
Received on Mon Jun 29 2015 - 10:44:01 BST
