Jonathan: when you say: You could describe a standard error with a `cell_methods` entry of `measurement: standard_deviation`, for instance, if we add `measurement` to the standard name table, meaning the ordinal number of a measurement of a given quantity. There does not have to a measurement dimension; using a standard name in `cell_methods` implies that the statistic applies to the complete range of the quantity named i.e. all possible measurements in this case. Can you provide an example just to make sure I understand ? very respectfully, randy
---------------------------------------- From: "Jonathan Gregory" <[email protected]> Sent: Monday, September 09, 2013 10:26 AM To: Subject: Re: [CF Metadata] #74: Allow sharing of ancillary variables among multiple data variables #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 jonathan): Dear all I tend to think, partly as a result of discussion in another ticket, that we should adopt a different solution for `number_of_observations` and `status_flag` on the one hand, and `standard_error` and `detection_minimum` on the other. Thus we could get rid of standard name modifiers, as Nan says; they are awkward and have caused confusion. As Randy says, the former two modifiers could become standard names for dimensionless quantities. As Nan says, this can't be done for the latter two, because they have units. Instead, I think we should put the information into `cell_methods`. It is possible to regard standard error and detection minimum as particular statistics in an ensemble of possible measurements of the same quantity, I would argue. If so, `cell_methods` is a natural place to put them, under an entry which applies to a notional dimension that runs over the members of this population. You could describe a standard error with a `cell_methods` entry of `measurement: standard_deviation`, for instance, if we add `measurement` to the standard name table, meaning the ordinal number of a measurement of a given quantity. There does not have to a measurement dimension; using a standard name in `cell_methods` implies that the statistic applies to the complete range of the quantity named i.e. all possible measurements in this case. Does this make sense to you? A nice consequence is that this would simplify the convention, because only the standard name and cell methods would determine the canonical units of the quantity. At the moment, the standard name modifier has to be considered as well. Cheers Jonathan -- Ticket URL: <https://cf-pcmdi.llnl.gov/trac/ticket/74#comment:40> CF Metadata <http://cf-pcmdi.llnl.gov/> CF Metadata
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