Hi all,

I'm trying to understand how to handle some climate data with a 360-day
calendar.  As I understand it
(http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.4/cf-conventions.ht
ml#calendar), this calendar uses 12-month years with exactly 30 days
each.  I have a few questions:

1) In this system, how long is a day in milliseconds?  Is it the normal
24*60*60*1000?  Or is it somehow scaled so that a year of 360 days has
the same number of milliseconds as an "average" Gregorian year?

2) Is there any way of translating (even roughly) between 360-day and
Gregorian calendars?  E.g. perhaps one could, for a given date-time,
calculate the fraction of a year that has elapsed and apply this in the
conversion?  Or is the comparison only meaningful in a statistical sense
(e.g. annual/seasonal averages)?

3) Would the most usual way to encode a CF time axis in a 360-day
calendar be to use "days since..."?  I guess if a day has a standard
length in (milli)seconds then one could also safely use "seconds
since..."?

4) Finally on practical note: I seem to remember that someone has
implemented the 360-day calendar using the Java library joda-time?  Is
this code available for re-use?

Thanks in advance,
Jon

--
Dr Jon Blower
Technical Director, Reading e-Science Centre
Environmental Systems Science Centre
University of Reading
Harry Pitt Building, 3 Earley Gate
Reading RG6 6AL. UK
Tel: +44 (0)118 378 5213
Fax: +44 (0)118 378 6413
[email protected]
http://www.nerc-essc.ac.uk/People/Staff/Blower_J.htm


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