#140: Clarifying the role of attributes on boundary variables.
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Reporter: davidhassell | Owner: cf-conventions@…
Type: enhancement | Status: new
Priority: medium | Milestone:
Component: cf-conventions | Version:
Resolution: | Keywords: boundary variable, attribute
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Comment (by jonathan):
Dear David
Thanks for your posting. I agree that we should resolve this for the sake
of CMIP6 and CF - we could still get it into 1.7 if we agree now about it.
I would be happy with what you suggest, but I think that Karl wouldn't be.
He think it's important that the bounds must have formula terms, so he
would not like to allow your "Implicit" case. For the sake of reaching an
agreement, I think it would be fine to require bounds to have formula
terms (as Karl prefers), but I still want to permit formula terms to have
bounds (as you and I prefer) and hence allow your "two methods" case.
That was the aim of the text I proposed in comment 7
If a parametric coordinate variable with a `formula_terms` attribute
(ref section 4.3.2) also has a `bounds` attribute, its boundary variable
must have a `formula_terms` attribute too. Because the same
`standard_name` must describe both variables, the formula must have the
same terms (as specified in Appendix D), but a different variable must be
named by the two `formula_terms` attributes for any term which depends on
the vertical dimension, because the boundary variables have one more
dimension. The boundary variables for these formula terms may also be
identified by `bounds` attributes of the formula terms variables. In that
case, the `formula_terms` of the boundary variable and the `bounds` of the
formula terms variables must be consistent.
which would be well-illustrated by your "explicit" and "two methods" CDL.
What do you think, Karl?
Cheers
Jonathan
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Ticket URL: <https://cf-trac.llnl.gov/trac/ticket/140#comment:11>
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