[CF-metadata] How to define time coordinate in GPS?

From: Jonathan Gregory <j.m.gregory>
Date: Wed, 20 May 2015 17:35:16 +0100

Dear Chris

> the elapsed time _should_ be correct. period. If it says X seconds since
> the epoch, then it should be X seconds since the epoch.
>
> I understand that someone may have made a mistake/used an inappropriate
> library, etc, such that there may be an off by-a-couple-seconds error in
> the elapse time. But are we really trying to include something in the
> standard to accommodate that?

Yes! Most applications aren't sufficiently precise to care about this (and
in the model world it doesn't arise), but there are some which care about the
leap seconds, it appears. That's what motivated the original enquiry. In the
real world UTC calendar (gregorian_utc), the leap seconds must be accounted
for in order to calculate and interpret the elapsed time correctly. In the
gregorian_nls calendar, they are ignored.

> There could be errors / lack of precision in ANY variable in a file --
> what's so special about this one?

I think it's complicated because of the two representations of time, either
as YMDhms, or as elapsed time. This complexity doesn't apply to other coords.

Best wishes

Jonathan
Received on Wed May 20 2015 - 10:35:16 BST