[CF-metadata] cell measures for non-horizontal planes

David Hassell d.c.hassell at reading.ac.uk
Wed Oct 7 09:37:48 MDT 2015


Hello,

I was wondering if anyone can help clear something up for me: Can an
"area" cell measure variable span non-horizontal axes? For example,
could you have an area cell measure for X-Z cells? And if so, what
could its standard name be? E.g.

  float cell_area(longitude, height):
      cell_area:measure = "area";
      cell_area:units = "m2";
      cell_area:standard_name = ?????????????

I know that the standard_name attribute is optional, thus the two part
question.

There is a standard name "cell_area" (= the horizontal area of a
gridcell), but not one for areas of arbitrarily orientated planes.

The conventions (section 7.2) do not explicitly disallow
non-horizontal planes (that's three negatives in half a sentence!),
but if they're allowed then the assumption is, I think, that the plane
of the area is implied by the variable's dimensions and there is no
applicable standard name. This is tricky if the cell measure variable
does have X and Y dimensions, as in example 7.3. This example uses the
standard name "area" for its cell measure variable, but this name is
not in the table - I presume that "cell_area" is meant. I'll raise a
defect ticket for this if required.

Many thanks and 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.hassell at reading.ac.uk



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