Hi Paul, Jim,
I'm not sure I follow the use of "inclusive" and "exclusive" (in
particular I'm not sure what you mean by "CF upper bounds are always
exclusive" - is this in the conventions?), but I agree that the upper
bounds are at:
1960-01-01 00:00:00
1961-01-01 00:00:00
etc.
to match up with the bounds values of
bounds_time = // "days since 1955-1-1 0:0:0.0"
0, 1826,
365, 2192,
etc.
All the best,
David
---- Original message from Jim Biard (10AM 12 Mar 15)
> Date: Thu, 12 Mar 2015 10:25:55 -0400
> From: Jim Biard <[email protected]>
> To: [email protected]
> Subject: Re: [CF-metadata] Overlapping time_bounds (running mean data)
> User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:31.0)
> Gecko/20100101 Thunderbird/31.5.0
>
> Paul,
>
> What you are doing is essentially perfect. Ferret is complaining,
> but Ferret complains about a lot of things that are correct. It
> assumes too much.
>
> There is one imperfection in your example: describing your upper
> bounds as inclusive. CF upper bounds are always exclusive, so your
> upper bounds should be 1960-01-01 00:00:00.0 and 1961-01-01
> 00:00:00.0. Your days since 1955-01-01 00:00:00.0 upper bound values
> in your example are correctly exclusive, so this isn't a "real"
> problem here, but I've found that thinking about the upper bounds
> the wrong way can lead to strangeness down the road, so I thought
> I'd point it out.
>
> Your example also raises a question in my mind, so I'll throw an
> off-track thought at you just for fun. Is there a driving reason why
> you are choosing midnight on July 2 for some intervals and noon on
> July 2 for others? I know that is the exact midpoint in each case,
> but my tendency would be to pick either midnight or noon and use
> that consistently. More specifically, I would pick YYYY-07-02
> 12:00:00.0 for all my time variable values. That's just me, but
> doing this is both valid (in particular since you have bounds that
> makes the input range clear) and places the value unambiguously on
> the same day in each year. This is more of a style issue, so don't
> feel compelled to change anything unless you feel like it.
>
> Grace and peace,
>
> Jim
>
> On 3/11/15 8:24 PM, Durack, Paul J. wrote:
> >Hi folks,
> >
> >I¹m generating a file which contains annual pentadal averaged data - so
> >effectively a 5-year running mean saved with an annual time step. The file
> >looks like:
> >
> >---
> >dimensions:
> > time = UNLIMITED ; // (56 currently)
> > bound = 2 ;
> > level = 26 ;
> > latitude = 180 ;
> > longitude = 360 ;
> >variables:
> > float time(time) ;
> > time:bounds = "bounds_time" ;
> > time:units = "days since 1955-1-1 0:0:0.0" ;
> > time:long_name = "time" ;
> > time:standard_name = "time" ;
> > time:calendar = "gregorian" ;
> > time:axis = "T" ;
> > float bounds_time(time, bound) ;
> >
> >
> >...
> >
> >data:
> >time = 913, 1278.5, 1644, 2009, 2374, 2739.5, 3105, 3470, 3835, 4200.5,
> > 4566, 4931, 5296, 5661.5, 6027, 6392, 6757, 7122.5, 7488, 7853, 8218,
> > 8583.5, 8949, 9314, 9679, 10044.5, 10410, 10775, 11140, 11505.5, 11871,
> > 12236, 12601, 12966.5, 13332, 13697, 14062, 14427.5, 14793, 15158,
> >15523,
> > 15888.5, 16254, 16619, 16984, 17349.5, 17715, 18080, 18445, 18810.5,
> > 19176, 19541, 19906, 20271.5, 20637, 21002 ;
> >bounds_time =
> > 0, 1826,
> > 365, 2192,
> > 731, 2557,
> > 1096, 2922,
> >...
> >
> >
> >---
> >
> >I¹m wondering what the most CF-like way of creating these bounds?
> >Currently the bounds are specified as:
> >
> >Index 1:2
> >1955-1-1 0:0:0.0 -> 1959-12-31 12:59:59.0
> >1956-1-1 0:0:0.0 -> 1960-12-31 12:59:59.0
> >
> >And time values as above:
> >Index 1:2
> >1957-7-2 0:0:0.0
> >1958-7-2 12:0:0.0
> >
> >When I try and load the file using Ferret, this throws a warning.. Which
> >makes me think I¹m not doing things correctly:
> >
> >Ferret v6.93
> >yes? use file.nc
> > *** NOTE: Axis definition error on axis: time. Bounds describe cells that
> >overlap one another
> > *** NOTE: Error in bounds "bounds_time" or bounds do not enclose point on
> >axis time
> > *** NOTE: Substituting coordinate midpoints
> >
> >Are there any tips for me regarding this, I wasn¹t able to find anything
> >clear (at least to me) in the v1.7.2 Draft CF document.
> >
> >Cheers,
> >
> >P
> >
> >_______________________________________________
> >CF-metadata mailing list
> >[email protected]
> >http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
>
> --
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David Hassell
National Centre for Atmospheric Science (NCAS)
Department of Meteorology, University of Reading,
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