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#79: Handling and formatting of vector quantities in CF -----------------------------+---------------------------------------------- Reporter: lavergne | Owner: [email protected] Type: enhancement | Status: reopened Priority: medium | Milestone: Component: cf-conventions | Version: Resolution: | Keywords: vector -----------------------------+---------------------------------------------- Comment (by jonathan): Dear Thomas I prefer the simplicity of your original idea, recently reproposed by Nan. I do not think it is a good idea to store more information in the container variable than is necessary. It is not necessary to identify the components, amplitude, angle etc. of a vector, since they do that themselves with their standard names. You just want to provide a way to group them. The second argument standard_names are not mandatory and sometimes "under approval", and vectors could need a way to be defined with "non standard" components strikes me as an argument ''against'' using the container variable to indicate which is the x-component, which the y-component, etc. Providing this facility might mean that users of new quantities would not bother to request standard names for them, and thus the container variable would become an alternative to standard names for identifying these quantities. That would make the use of the CF standard more complicated for software trying to find what it wants in a file. Rather, I think that the variables the container points to should be required to have standard names - I'm sure that we have been through this before :-) Your original use-case was to make it easier to identify the groups of variables that together form a vector. The simplest kind of container will fulfil that need. Use of `cf_role="vector"` looks like a good idea to me. The term "container" might be slightly ''too'' general, though. We also call `grid_mapping` a container variable, but its purpose is different. "Group" could be a good term. I still think it would be fine to have special standard names for these vector groups, but equally we could have a new controlled vocabulary. In either case, it should be stated in the vocabulary which standard names were allowed as components of a group with a particular group name. So I would favour something like your original version and Nan's recent one {{{ int drift_vector; drift_vector:group_name = "sea_ice_displacement"; drift_vector:cf_role="vector"; drift_vector:components = "dX dY dir" ; }}} Even more simply, if it has a `group_name` (rather than a `standard_name`), perhaps that identifies its purpose, and the `cf_role` could be omitted. Best wishes Jonathan -- Ticket URL: <https://cf-pcmdi.llnl.gov/trac/ticket/79#comment:63> CF Metadata <http://cf-pcmdi.llnl.gov/> CF Metadata This message came from the CF Trac system. To unsubscribe, without unsubscribing to the regular cf-metadata list, send a message to "[email protected]" with "unsubscribe cf-metadata" in the body of your message.
