Dear Randy I agree with what you write. You could list the alternative sets of three coordinates each all as auxiliary coord vars, and distinguish them with standard_names; presumably you would want to propose some new standard_names. That would be fine and quite simple to do.
In addition, you could propose new grid_mappings. Up to now grid_mappings have been for 2D coordinate systems, but you would want something in 3D, I think. If it's likely generally useful, it would interesting to see a proposal of what it might look like. There is already an agreed change to the CF standard to allow more than one grid_mapping for a given data variable. This was proposed by Mark Hedley in ticket 70 https://cf-pcmdi.llnl.gov/trac/ticket/70 and will go in CF 1.7. In response to Jim's comment, I would say that the data variable does have a coordinate system; it's defined by the various coordinate variables that the data variable is associated with, either 1D (Unidata) coordinate variables or auxiliary coordinate variables. The role of the grid_mapping is to make explicit the relationship among the coordinate variables of the space in which the data variable exists. Best wishes Jonathan _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
