Dear John > Suppose we added the UTC_Calendar to CF, which tracks leap seconds > etc. So if one had the time coordinate "days since 1800-01-01" with > values = "0,1,2,3..." and we need the resulting coordinates to be > "1800-01-01", "1800-01-02", "1800-01-03", "1800-01-04",.... which in > this calendar gives an uneven number of seconds between coordinates. > > So all timeUnits (except seconds) now mean "increment the calendar > field", not "add x secs to base", that is, its calendar dependent if > any timeUnit implies a fixed number of seconds.
In fact that also raises the same problem as I did in my last email. If a second is removed, there will be some occasions when adding 1 day to a given time will not have an obvious meaning, because the corresponding time a day later may not exist in the calendar. A rule is needed to resolve that. > In that case, then fractional values may not make sense(?) It will depend on the calendar, presumably. In the 360_day calendar, all the units of time have fixed length. In the UTC calendar, none of them do except seconds, apparently. Fractions are OK with fixed-length units. In the 360_day calendar, 0.5 year means 180*86400 seconds exactly. Cheers Jonathan _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
