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

[Peter McCartney]

We convert the campbell fields into a datetime field and include both types
into our database. Many of our researchers have existing scripts to use what
campbell calls "julian day" and julian hour. It gets a bit tricky around
midnight, since the cambell's hour field goes from 0-23 and in the date time
field 0000 hours is 1200 hours the previous day. 

Since they come as two different fields, we don't encounter the YYYYDDD
format in a single attribute, although I understand there are many alternate
ascii formats you can configure the thing to use.

Peter McCartney (peter.mccartney at asu.edu)
Center for Environmental-Studies
Arizona State University
 


-----Original Message-----
From: Tim Bergsma [mailto:tbergsma at kbs.msu.edu] 
Sent: Monday, March 24, 2003 7:51 AM
To: Scott Chapal
Cc: Peter McCartney; eml-dev at ecoinformatics.org
Subject: Re: Julian Date format -- interval not dateTime (my thought)


Campell Scientific dataloggers, the workhorses of weather data, normally
record date with two fields:  year and day-of-year.  If you want to document
the  raw data file, you're stuck with that.  (I guess technically you could
say date wasn't recorded.) Most of us probably transform year/day of year to
generate a 'real' date, at least for 'value-added' products.

Incidentally, I discovered by accident a function in MSAccess called
DateSerial(year,month,day).  At first it doesn't look very helpful, but if
you hard-code the month as 1, you can put any positive integer at all for
day, and get a valid date in return!  For instance, the 365th day of January
2003 is 12-31-2003.

So back to the point, I wouldn't be at all surprised if YYYYDDD is
ubiquitous, as a merge of the standard Campbell fields.  The issue is likely
to come up for others.  If someone (Scott) finds a nice way of handling it,
I favor the R&D strategy (rob and duplicate).

Tim.

Scott Chapal wrote:
> 
> Peter McCartney <peter.mccartney at asu.edu> writes:
> 
> > julian days would be ratio.
> 
>  day-of-year ? :)
> >
> > YYYYDD would NOT be ordinal - it would be an odd representation of 
> > dateTime that would be really confusing and not supported by most 
> > processing systems. Its like trying to write 111 deg, 1 min, 1 
> > second as 111 deg, 61 seconds - in priciple, its correct, but why 
> > would you do it?
> 
> I wouldn't.
> 
> But I have seen dates encoded that way.  I'm guessing by data-loggers 
> that were attempting to conserve bits.?  But then again, I've seen 
> dates formatted a lot of silly ways.
> 
> dateTime non-Standard YYYYDDD - Year-and-day-of-year
> 
> -Scott
> 
> > Peter McCartney(peter.mccartney at asu.edu)
> > Center for Environmental Studies
> > Arizona State University
> >
> >
> > -----Original Message-----
> > From: Tim Bergsma [mailto:tbergsma at kbs.msu.edu]
> > Sent: Thursday, March 20, 2003 11:51 AM
> > To: Scott Chapal
> > Cc: eml-dev at ecoinformatics.org; Henshaw, Don; Spycher, Gody
> > Subject: Re: Julian Date format -- interval not dateTime (my 
> > thought)
> >
> >
> > Scott,
> >
> > Did anyone reply to this yet?  I think the answers are yes and yes 
> > (and yes), but I'm no expert yet on date formats (conveniently, I 
> > was out of the country when that part of EML got finalized).
> >
> > Tim.
> >
> > Scott Chapal wrote:
> > >
> > > So..
> > >
> > > "Day of Year" 1-365(6)
> > >
> > > measurementScale: RATIO
> > > unit: nominalDay
> > >
> > > And, YYYYDDD would be ORDINAL (and a poor choice of date format)?
> > >
> > > -Scott
> > >
> > > Matt Jones <jones at nceas.ucsb.edu> writes:
> > >
> > > > I agree.  We created the unit 'nominalDay' precisely for this 
> > > > purpose. It represents an integer number of days.
> > > >
> > > > Matt
> > > >
> > > > Tim Bergsma wrote:
> > > > > 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.
> > >
> > > --
> > > \SEC
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> >
> > --
> > 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 
> > _______________________________________________
> > eml-dev mailing list
> > eml-dev at ecoinformatics.org 
> > http://www.ecoinformatics.org/mailman/listinfo/eml-dev
> 
> --
> \SEC
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-- 
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
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