[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

20050418: udunits documentation



Jeremy,

> Date: Thu, 14 Apr 2005 16:11:16 -0400
> From: Jeremy Rolph <address@hidden>
> To: address@hidden
> Subject: udunits documentation

The above message contained the following:

> Just curious, I am trying to use the udunits package and I am using
> PMEL TAO buoy data and I was comparing your reference date of
> 5/23/1968 00UTC as true Julian Day 2,400,000

I'm the author of the UDUNITS package and I'm I'm afraid I don't know
what you're talking about.  The date 1968-05-23 isn't a "reference date"
in the UDUNITS package (i.e., that date isn't used anywhere in the
package).  Also, the test program

    #include <stdio.h>
    #include <udunits.h>
    int
    main()
    {
        printf("Julian day number of 1968-05-23 is %ld\n",
            gregdate_to_julday(1968, 5, 23));
        return 0;
    }

prints

    Julian day number of 1968-05-23 is 2440000

rather than "2400000".

Perhaps you need to talk to the PMEL TAO buoy data people rather than
the UDUNITS package developer.

> to a date in one of the
> TAO netCDF files and simply subtracted the reference date from the
> dates in my file and I got a result of 51299.  I did some generic
> math and this results in a date roughly 140 yrs after 1968.  This
> obviously makes no sense.  I did more research and found this link on
> google.com:
> http://my.unidata.ucar.edu/content/software/netcdf/time/0057.html
> 
> On this page they are referencing 2,440,000 as 5/23/1968.  Which is
> correct.  If it is the second, 2,440,000, I think the documentation on the
> udunits pages should be updated to avoid further confusion.  Also, I
> should be using the msec as being since 00UTC rather than 12 UTC?
> 
> Let me know if I am wrong and which value is the correct one to use.
> 
> Thanks,
> Jeremy J. Rolph
> Center for Ocean Atmospheric Prediction Studies

Regards,
Steve Emmerson

> NOTE: All email exchanges with Unidata User Support are recorded in the
> Unidata inquiry tracking system and then made publicly available
> through the web.  If you do not want to have your interactions made
> available in this way, you must let us know in each email you send to us.


NOTE: All email exchanges with Unidata User Support are recorded in the Unidata inquiry tracking system and then made publicly available through the web. If you do not want to have your interactions made available in this way, you must let us know in each email you send to us.