[CF-metadata] date and time

From: Jonathan Gregory <j.m.gregory>
Date: Sat, 25 Oct 2008 09:07:22 +0100

Dear John

> Uh, to an observing systems/cyberinfrastructure person, ALL time
> values have errors, _especially_ those from devices.

I think the point is, as Nan says, that the data user will want there to be one
"time" which is to be regarded as coordinated, as the "true" time, in the sense
that data values with the same coordinate of time are to be regarded as truly
simultaneous. It is up to the data-writer to provide this coordinate if
possible as they are typically better able to do it than the user. This one has
the standard_name of "time".

Regarding time_from_device, I would say that is not clear to me, because *all*
times come from some device, even if it is an atomic clock determining the UTC
standard! What about time_from_instrument. Would that be clearer than sensor?
I think a sensor is a sampler in the existing name
  temperature_of_sensor_for_oxygen_in_sea_water
but perhaps Nan or Roy could comment.

> mission_elapsed_time is fine.
OK.

My point about redundancy refers particularly to the time within year and day.
Do you mean the device is giving you both the time (elapsed since some
reference) and its components (time within year and day etc.). The time and
its components are related by well-defined arithmetic. Do you want to record
them all separately? If so, why? Perhaps for completeness, to be on the safe
side?

Thanks for the discussion. Best wishes

Jonathan
Received on Sat Oct 25 2008 - 02:07:22 BST