On Mon, May 11, 2015 at 11:58 AM, Jim Biard <jbiard at cicsnc.org> wrote:
> I agree that in many cases the implications of mistakes in which calendar
> and/or time system was used when creating or using a given file are often
> negligible.
>
there is that...but that wasn't my only point.
> This is one of those situations where it most often doesn't really matter,
> but it sometimes can matter a lot. If you are working with 1 km resolution
> data from a satellite that is moving at ~7 km/sec, then even a 1 second
> discrepancy is significant. If the time span over your full set of files is
> long enough that a leap second event is included, then even time
> differences taken between points within your set of files can be wrong.
>
sure, but if you choose your epoch carefully (or even have the same epoch
in all your files) then whether this is a problem is a function of how you
work with the time axis in the client -- no how it it is encoded in the
file.
I guess what I'm getting at is that the choice of "time since an epoch"
encoding really does make all this safer.
That being said:
Because this is something that is often insignificant, I proposed a
> combination clarified definitions, and additional attributes and/or
> optional modifiers to calendar names that allow for greater precision when
> it matters without sacrificing backward compatibility for large numbers of
> datasets.
>
Exactly -- better precision in the definitions is only a good thing -- but
I think we can relax about older files (and older CF versions) being
ambiguous -- anyone for whom it matters should know how to deal with it.
-Chris
--
Christopher Barker, Ph.D.
Oceanographer
Emergency Response Division
NOAA/NOS/OR&R (206) 526-6959 voice
7600 Sand Point Way NE (206) 526-6329 fax
Seattle, WA 98115 (206) 526-6317 main reception
Chris.Barker at noaa.gov
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Received on Tue May 12 2015 - 09:52:19 BST
