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[UDUNITS #KHO-415432]: time attribute: hours since 2010-1-1 12 ('naked hour')



Dennis,

It does appear that the UDUNITS package doesn't correctly handle a "naked hour" 
in a timestamp.

I'll see about fixing this ASAP.

Thanks for sending this in.

> Hello,
> I downloaded 3-hrly TRMM netCDF files from NASA's mirador server.
> A sample file dump for 3B42.20090731.12.7A.nc looks like:
> 
> %> ncdump -v time 3B42.20090731.12.7A.nc
> 
> netcdf \3B42.20090731.12.7A {
> dimensions:
> time = UNLIMITED ; // (1 currently)
> longitude = 1440 ;
> latitude = 400 ;
> variables:
> double time(time) ;
> time:units = "hours since 2009-7-31 12" ;   <========
> 
> [SNIP a bunch of variables]
> 
> // global attributes:
> :Conventions = "COARDS" ;                   <=========
> :calendar = "standard" ;
> :comments = "file created by grads using lats4d
> available from http://dao.gsfc.nasa.gov/software/grads/lats4d/"; ;
> :model = "geos/das" ;
> :center = "gsfc" ;
> data:
> 
> time = 0 ;
> }
> ============
> Each file has its own unique time base units attribute which matches
> the date in the file name.
> ============
> I then used the NCO operator 'ncrcat' to concatenate multiple files.
> The result was a file in which the time variable was not rebased
> correctly. Also, I tried using NCL and it had a problem also.
> 
> Rather than go into detail here, please take a look at the
> full description of the issue at the NCO 'help' page. Thread:
> 
> ncrcat: time rebase [version "4.3.9"]
> 
> http://sourceforge.net/p/nco/discussion/9830/thread/56389da4/
> 
> This includes Charlie Zender's response in which he states:
> 
> "...A naked integer for the HH hour is not correctly recognized."
> 
> "I am uncertain whether this is a problem with UDUnits
> not supporting a format it says it does, or whether TRMM
> data uses a units format that UDUnits does not explicitly support.
> I suspect the latter. If not, please forward this problem to
> Unidata for fixing."
> 
> ==============
> I could make a few sample files (~14MB each) available if this
> would be of use.
> 
> Regards
> Dennis Shea, NCAR/CGD

Regards,
Steve Emmerson

Ticket Details
===================
Ticket ID: KHO-415432
Department: Support UDUNITS
Priority: Normal
Status: Closed


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