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[THREDDS #YJM-623796]: NetCDF Subset Service (NCSS) and UDUNITS: wrong datetimes for climatologies

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  • Subject: [THREDDS #YJM-623796]: NetCDF Subset Service (NCSS) and UDUNITS: wrong datetimes for climatologies
  • Date: Wed, 06 Jul 2011 11:08:35 -0600
John,

> Hi TDS and UDUNITS Folks,
> Just noticed the following bug: for monthly climatologies where the year is
> set to "0000", NetCDF Subset Service (NCSS) is erroneously showing a year of
> 0001. Here's the result of an AVHRR SST monthly climatology in NCSS:
> 
> http://oceanwatch.pifsc.noaa.gov/thredds/ncss/grid/climatologies/PF5_SST_Climatology_Monthly_1985_2001.nc?var=sst&latitude=21&longitude=-161&temporal=all&time_start=0001-01-16T06%3A00%3A00Z&time_end=0001-12-16T01%3A20%3A05Z&time=0001-01-16T06%3A00%3A00Z&vertCoord=&accept=csv&point=true
> 
> date,lat[unit="degrees_north"],lon[unit="degrees_east"],sst[unit="degrees
> Celsius"]
> 0001-01-16T06:00:00Z,21.0,-161.0,24.6
> 0001-02-15T16:29:05Z,21.0,-161.0,24.45
> 0001-03-17T02:58:12Z,21.0,-161.0,24.375
> 0001-04-16T13:27:18Z,21.0,-161.0,24.45
> 0001-05-16T23:56:24Z,21.0,-161.0,25.125
> 0001-06-16T10:25:30Z,21.0,-161.0,25.875
> 0001-07-16T20:54:36Z,21.0,-161.0,26.475
> 0001-08-16T07:23:42Z,21.0,-161.0,27.0
> 0001-09-15T17:52:48Z,21.0,-161.0,27.225
> 0001-10-16T04:21:54Z,21.0,-161.0,27.15
> 0001-11-15T14:51:00Z,21.0,-161.0,26.325
> 0001-12-16T01:20:05Z,21.0,-161.0,25.2
> 
> 
> If you list the time variable with OPeNDAP, you get the following
> (units = "hour since 0000-01-01 00:00:00"):
> 
> http://oceanwatch.pifsc.noaa.gov/thredds/dodsC/climatologies/PF5_SST_Climatology_Monthly_1985_2001.nc.ascii?TIME[0:1:11]
> 
> Dataset {
> Float64 TIME[TIME = 12];
> } climatologies/PF5_SST_Climatology_Monthly_1985_2001.nc;
> ---------------------------------------------
> TIME[12]
> 366.0, 1096.485, 1826.97, 2557.455, 3287.94, 4018.425, 4748.91,
> 5479.395, 6209.88, 6940.365, 7670.85, 8401.335
> 
> 
> Running the above numbers through udunits, it seems the problem is actually
> with udunits:
> 
> 
> > udunits
> You have: 366 hour since 0000-01-01 00:00:00
> You want:
> Definition: "1317600 seconds since 1-01-01 00:00:00.00 UTC"
> "366 hour since 0000-01-01 00:00:00" is 1-01-16 06:00:0 UTC
> 
> 
> It lists the year simply as "1". In contrast, ncWMS/Godiva2 correctly
> identifies the dates as belonging to year 0000:

There is no year 0 (see <http://en.wikipedia.org/wiki/AD>), so best not to use 
it.

> http://oceanwatch.pifsc.noaa.gov/thredds/godiva2/godiva2.html?server=http://oceanwatch.pifsc.noaa.gov/thredds/wms/climatologies/PF5_SST_Climatology_Monthly_1985_2001.nc
> 
> Thanks for your attention to this detail. A further note of interest is that
> NCSS does not handle milliseconds, so in my application I'm having to round
> to seconds and hope I get a result.
> Cheers,
> John Maurer
> Pacific Islands Ocean Observing System (PacIOOS)
> University of Hawaii at Manoa

Regards,
Steve Emmerson

Ticket Details
===================
Ticket ID: YJM-623796
Department: Support UDUNITS
Priority: Normal
Status: Closed