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#74: Allow sharing of ancillary variables among multiple data variables ---------------------------------------+------------------------------------ Reporter: [email protected] | Owner: [email protected] Type: enhancement | Status: new Priority: medium | Milestone: Component: cf-conventions | Version: Resolution: | Keywords: "ancillary data" "standard name modifiers" ---------------------------------------+------------------------------------ Comment (by biard): So, now we are back to where we were before. Part of this proposal of Jonathan's still gives me heartburn. Expressed this way, the only way to know (apart from having it stated in the variable name, which is unreliable) that the variable contains a standard deviation of temperature and not temperature is to reference the cell_methods attribute. The word "measurement" itself would become a standard name. It would not be a proxy or placeholder. It would have a status equivalent to longitude or time, and represent an ordinal counting of samples. Another similar example is the use of the word "area" in cell methods. Even though area may not ever be expressed directly in any variable, you can validly state in the cell_methods attribute that the variable values represent an average over the area of the cell. Thus (if I understand correctly), "measurement: standard deviation" is stating that the operation "calculate the standard deviation" was performed on all the individual measurements that fell in this cell. I think it might be more restrictively understood as stating that the only dimension over which the operation was performed was the measurement dimension, and all other dimensions (lat and lon, for example) were held constant. Jonathan, I'm not sure how or why you shifted from the dimension "measurement" having a size greater than one to having a size equal to one in your example. That bit just confused me. If I am close to on target, the suggested ensemble of variables would be something like this. dimensions: time=N; variables: int time(time); ... float a(time); a:long_name="This is the average temperature measurement"; a:standard_name="sea_water_temperature"; a:units="K"; a:cell_methods="measurement: mean"; a:ancillary_variables="b"; float b(time); b:long_name="This is the standard deviation of the average temperature measurement"; b:standard_name="sea_water_temperature"; b:units="K"; b:cell_methods="measurement: standard_deviation"; Is that about right, Jonathan? Grace and peace, Jim -- Ticket URL: <https://cf-pcmdi.llnl.gov/trac/ticket/74#comment:43> 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.
