i think a crucial property of coordinates is that their dimensions are a subset of the variable's dimensions. otherwise one cant assign the correct coordinate.
the length of a char valued coordinate is an exception, really char(n) is logically the same as string. while a dim=1 coordinate could be used, it would violate that simple principle for no obvious gain. scalar here is preffered i think. we added some language to CF recently to clarify this. not sure where it is. john On Mon, Dec 21, 2015 at 8:49 AM, Jim Biard <jbi...@cicsnc.org> wrote: > David, > > I've not come across this particular case, but I've had cases where the > ancillary data that I wish to store has less dimensions than the > corresponding parent field. The Conventions seem to require that the > dimensions all match. I'm of the opinion that it should not be so > restrictive. > > In your particular instance, what is the significance of your time > variable? > > Grace and peace, > > Jim > > > On 12/21/15 10:41 AM, David Hassell wrote: > > Hello, > > I was wondering if anyone has ever had use for an ancillary variable > (or data variable pointed to from a formula_terms attribute), having a > size 1 dimension which the "parent" field does *not* have. The > convention do not say anything about this. > > For example: > > dimensions: > t = 1; > x = 96; > y = 73; > > variables: > float q(x, y) ; > q:standard_name = "specific_humidity" ; > q:units = "g/g" ; > q:ancillary_variables = "q_error_limit" ; > > float q_error_limit(t, x, y) > q_error_limit:standard_name = "specific_humidity standard_error" ; > q_error_limit:units = "g/g" ; > > > Similary for a scalar coordinate variable, which is logically > equivalent to the size 1 dimension case (this time shown on a formula > terms variable): > > dimensions: > x = 96; > y = 73; > z = 19; > > variables: > float q(z, x, y) ; > q:standard_name = "specific_humidity" ; > q:units = "g/g" ; > > float z(z): > z:standard_name = "atmosphere_hybrid_height_coordinate"; > z.formula_terms = "a: var1 b: var2 orog: var3" > > float var3(x, y): > time:coordinates = "time"; > > float time: > time:standard_name = "time"; > time:units = "days since 2000-12-1"; > > > Thanks for your help, > > All the best, > > David > > > -- > David Hassell > National Centre for Atmospheric Science (NCAS) > Department of Meteorology, University of Reading, > Earley Gate, PO Box 243, > Reading RG6 6BB, U.K. > > Tel : +44 118 3785613 > E-mail: d.c.hass...@reading.ac.uk > _______________________________________________ > CF-metadata mailing > listcf-metad...@cgd.ucar.eduhttp://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > > > -- > [image: CICS-NC] <http://www.cicsnc.org/> Visit us on > Facebook <http://www.facebook.com/cicsnc> *Jim Biard* > *Research Scholar* > Cooperative Institute for Climate and Satellites NC <http://cicsnc.org/> > North Carolina State University <http://ncsu.edu/> > NOAA National Centers for Environmental Information > <http://ncdc.noaa.gov/> > *formerly NOAA’s National Climatic Data Center* > 151 Patton Ave, Asheville, NC 28801 > e: jbi...@cicsnc.org > o: +1 828 271 4900 > > *Connect with us on Facebook for climate > <https://www.facebook.com/NOAANCEIclimate> and ocean and geophysics > <https://www.facebook.com/NOAANCEIoceangeo> information, and follow us on > Twitter at @NOAANCEIclimate <https://twitter.com/NOAANCEIclimate> and > @NOAANCEIocngeo <https://twitter.com/NOAANCEIocngeo>. * > > _______________________________________________ > CF-metadata mailing list > CF-metadata@cgd.ucar.edu > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata > >
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