[CF-metadata] CDM calendar date handling

From: John Caron <caron>
Date: Fri, 19 Aug 2011 10:28:04 -0600

On 8/19/2011 7:48 AM, Lynnes, Christopher S. (GSFC-6102) wrote:
> On Aug 19, 2011, at 7:54 AM, Jon Blower wrote:
>
>> Hi Chris,
>>
>> Does the calendar system usually define whether leap-seconds are taken into account or not?
> Generally speaking, I don't believe so, if only because calendar systems usually go down to the day granularity. Seconds-based doordinate time standards, such as UTC and TAI do, because they have to. Julian date (NOT the day of year many associate with the name) is an exception, with its fractional dates.
>
>> In other words, given knowledge of which calendar system is in use, could a library make the correct calculation? Or is other information needed too?
>

In my limited understanding, a calendar system might track leap seconds
or not. If it does, then all calendar fields (except seconds and
millisecs) would be variable length. But for any given calendar, the
interval (in seconds) between two valid dates would be well defined. Of
course, these intervals will differ between calendars.

Therefore, one can talk about a "correct" implementation of a calendar
system, and one can talk about the difference between two calendar
systems, one of which is the correct one to use in some context.
Otherwise, im not sure there really is a "correct calculation", or at
least that might be a confusing way to state the issue.
Received on Fri Aug 19 2011 - 10:28:04 BST