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[CF-metadata] Handling time when date is "missing"

From: Jim Biard <jbiard>
Date: Tue, 25 Oct 2016 16:18:59 -0400

Ajay,

I'm pretty certain that a file with fill values in a true time
coordinate variable will cause most every software package to have a
fit. It will also likely fail all CF compliance checkers.

Do you have any "alternative" method to determine the rest of the date?
If so, I'd suggest doing the best job you can of reconstructing the full
date/time for the time axis and adding a quality variable that would
mark those time steps as being provisional.

Another approach is to make a time variable that is not a coordinate
variable. You could have something like:

dimension time = UNLIMITED ;

# This variable holds your acquired time stamp information.
#
variable acq_time(time):
     :_FillValue = -1.0e20 ;

# This variable holds your notional time coordinate.
#
variable time(time):

variable data(time):


Or, you could dispense with a true time coordinate variable all together.

dimension sample = UNLIMITED ;

# This variable holds your acquired time stamp information.
#
variable acq_time(sample):
     :_FillValue = -1.0e20 ;

variable data(sample):
     :coordinates = "acq_time" ;


Both of these approaches avoid the problem of having fill values in a
true coordinate variable.

Grace and peace,

Jim

On 10/25/16 2:07 PM, Ajay Krishnan - NOAA Affiliate wrote:
> Hi All,
>
> I have a user that's converting some IMMA format files to CF compliant
> NetCDF files.
>
> The problem is that, we've run into several measurements where just
> the hour of measurement has been recorded without the corresponding
> "date". We would prefer not to omit these data in the conversion,
> because they are considered valid measurements (and play a role in
> monthly summary statistics)
>
> How do we represent this in a valid CF NetCDF format since we can't
> use _FillValues for 'time'? Any suggestions for handling such special
> cases?
>
> Thanks,
> Ajay
>
>
>
>
>
>
> _______________________________________________
> CF-metadata mailing list
> CF-metadata at cgd.ucar.edu
> http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata

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Received on Tue Oct 25 2016 - 14:18:59 BST

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