[CF-metadata] how to use time zones?

From: Wright, Bruce <bruce.wright>
Date: Tue, 10 Feb 2009 08:04:01 -0000

Hi Nan,

I don't know how CF handles time zones, but I thought it might be worth pointing out that the Wikipedia page on ISO 8601 is quite useful. The relevant section: http://en.wikipedia.org/wiki/ISO_8601#Time_zone_designators offers the following ways of representing times in zones other than UTC:
   <time>Z
   <time>?hh:mm or <time>?hhmm
   <time>?hh
With + being ahead (i.e. East) of UTC, which is consistent with your example below.

Best regards,
Bruce

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Bruce Wright Senior IT Architect 
Met Office FitzRoy Road Exeter EX1 3PB United Kingdom 
Tel: +44 (0)1392 886481 Fax: 0870 9005050 
E-mail: bruce.wright at metoffice.gov.uk http://www.metoffice.gov.uk 
-----Original Message-----
From: cf-metadata-bounces at cgd.ucar.edu [mailto:cf-metadata-bounces at cgd.ucar.edu] On Behalf Of Nan Galbraith
Sent: 09 February 2009 14:41
To: cf-metadata at cgd.ucar.edu
Subject: [CF-metadata] how to use time zones?
We use UTC for everything, but someone on another mailing list recently raised the issue of time zones, so I wondered how CF handles them. There's an example in the CF manual using local time:
seconds since 1992-10-8 15:15:42.5 -6:00
  indicates seconds since October 8th, 1992 at 3 hours, 15
  minutes  and  42.5 seconds in the afternoon in the time zone
  which is six hours to the west of Coordinated Universal Time
  (i.e.  Mountain Daylight Time).
which implies the way time zones should be expressed, but I couldn't find an actual 'rule' anywhere.
I don't have a copy of ISO 8601 but found this*:
Regarding Time Zones, it is common for those East of Greenwich to be treated as Positive, and for those to the West (i.e. the Americas) to be treated as Negative.
This is also defined towards the end of the ISO 8601 standard.
Should something similar be spelled out in the CF manual, or is the example clear enough?
Thanks -
Nan
*(What Is ISO 8601?   Ian Galpin, 1997-Feb-04,  mit.edu)
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* Nan Galbraith                        (508) 289-2444 *
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Received on Tue Feb 10 2009 - 01:04:01 GMT