Allow sharing of ancillary variables among multiple data variables
|Reported by:||rhorne@…||Owned by:||davidhassell|
|Keywords:||"ancillary data" "standard name modifiers"||Cc:|
Currently it is not possible for multiple data variables to share an ancillary variable.
Augment the conventions to allow two or more data variables to share an ancillary variable.
Here is an example of a convention, which dovetails with the existing conventions, to provide this capability:
swpt:standard_name="sea_water_potential_temperature"; swpt:ancillary_variables="nobs flags"; . .
. . sws:standard_name="sea_water_salinity"; sws:ancillary_variables="nobs flags"; . .
. . nobs:standard_name="sea_water_potential_temperature sea_water_salinity number_of_observations"; . .
. . flags:standard_name="sea_water_potential_temperature sea_water_salinity status_flag"; flags:flag_values = 0, 1, 2; flags:flag_meanings = "valid invalid unknown"; . .
Change the text in the CF metadata conventions section 3.3 that reads
"A standard name is associated with a variable via the attribute standard_name which takes a string value comprised of a standard name optionally followed by one or more blanks and a standard name modifier (a string value from Appendix C, Standard Name Modifiers)."
"A standard name is associated with a variable via the attribute standard_name which takes a string value that can have either of two forms. The first form is a standard name alone. The second form is a blank-separated list beginning with one or more standard names and ending with a single standard name modifier (i.e. standard_name [standard_name ...] standard_name_modifier). The standard name modifiers are defined in Appendix C, Standard Name Modifiers. This second form permits a single variable to provide ancillary data (see section 3.4) for two or more variables where each has a unique standard name."
Changes to CF software tools are required. For example, the CF_checker, which validates the standard_name attribute needs to change. However, it does not require any change to software that uses the complete attribute simply as an identifying string (e.g. to label plots, etc.)
Change History (59)
comment:58 Changed 3 months ago by davidhassell
- Owner changed from cf-conventions@… to davidhassell
- Status changed from new to accepted