Julian Date format -- interval not dateTime (my thought)

[Tim Bergsma]

Scott,

I was also wondering about "this advice".  I was taught somewhere not to
confuse Julian Day with day-of-year.  I use day-of-year, but I don't
really know what Julian Day is, and therefore hesitate to say too much. 
With regard to "saying that something takes 200 Julian Days", this is
clearly the same concept as eml dictionary unit nominalDay.

Tim.

Scott Chapal wrote:
> 
> Was there ever any determination about Julian Day?
> 
> What are we calling Julian Day in EML any way?
> 
> YYYYddd or ddd ??
> 
> David's numbers are what?  dddYYYY?
> 
> Or does this advice pertain?  "The system of Julian days should not be
> confused with the simpler system of the same name which associates a
> date with the number of days elapsed since January 1st of the same
> year (according to which 2000-12-31 is day 366 of the year 2000)."
> 
> Because the 'real' Julian Day is used in astronomy to number
> chronological days...
> 
> So,
> 
> ddd     - RATIO
> YYYYddd - ORDINAL
> 
> Or just other dateTime formats??
> 
> -Scott
> 
> David Blankman <dblankman at lternet.edu> writes:
> 
> > Don,
> >
> > I am not sure what the correct representation of Julian dates would
> > be. My sense is that the Julian date scale is actually an INTERVAL
> > scale not a dateTIME scale; arithmetic calculations are consistent,
> > that is, 2451919 - 2451819 gives the same value as 2351919 - 2351819.
> > It probably also makes sense to say that something that takes 200
> > julian days  = 2 * 100 julian days. My first thought was that it was a
> > ratio scale, but it is more like the celcius scale than the kelvin
> > scale in that the 0 on the julian scale is an arbitrary one.
> >
> >
> > The julian date scale does not suffer from the problems that are
> > associated with a standard calendar scale, that is, the only unit is
> > the day and the fraction of a day; there is nothing like Feb 20 - Jan
> > 20 representing a different number of days than Aug 20 - July 20.
> 
> > I would appreciate enl-dev feedback on that.
> >
> > David
> >
> > Henshaw, Don wrote:
> 
> > >  On another topic:
> >
> > > Can a julian date be represented in the format string for
> > > measurementScale of datetime
> >
> > > i.e., YYYYddd
> > >  Other notes (being rather picky): pertaining to
> > > eml-unitDictionary.xml (2.0.0)
> 
> --
> \SEC
> _______________________________________________
> eml-dev mailing list
> eml-dev at ecoinformatics.org
> http://www.ecoinformatics.org/mailman/listinfo/eml-dev

-- 
Tim Bergsma
LTER Information Manager
W.K. Kellogg Biological Station
Michigan State University
Hickory Corners, MI   49060
269/671-2337
tbergsma at kbs.msu.edu
http://lter.kbs.msu.edu