# Clarify some formula terms definitions # Moderator [TBD]
# Moderator Status Review [last updated: YYYY-MM-DD] Brief comment on current status, update periodically # Requirement Summary The formulas for computing non-parametric vertical coordinates are in general well defined, but in some cases the allowed units and standard names of some of the formula terms are not stated. It is possible to infer the units by a dimensional analysis of the formula, and to ascertain that some terms require identical units to particular other terms. However, it would be better to state these requirements explicitly to assist data providers and anyone who writes software to carry out the computation. The changes needed are: * For [ocean_double_sigma_coordinate](https://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html#_ocean_double_sigma_coordinate) that `a`, `z1` and `z2` must all have _identical_ units of (any) length (to ensure that the tanh operand is correct). * For [ocean_s_coordinate](https://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html#_ocean_s_coordinate) that `a` and `b` must be dimensionless and `depth_c` must have units of length. * For [ocean_s_coordinate_g1](https://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html#_ocean_s_coordinate_generic_form_1) the `computed_standard_name` and standard names of `C` and `depth_c` need defining. * For [ocean_s_coordinate_g2](https://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html#_ocean_s_coordinate_generic_form_2) the `computed_standard_name` and standard names of `C` and `depth_c` need defining. The last two points are brought in from https://github.com/cf-convention/discuss/issues/84 # Technical Proposal Summary For the relevant terms, a few lines are added to [Appendix D: Parametric Vertical Coordinates](https://cfconventions.org/Data/cf-conventions/cf-conventions-1.8/cf-conventions.html#parametric-v-coord). The [conformance document](https://cfconventions.org/requirements-and-recommendations.html) is updated to include a check on the units. # Benefits As well bringing clarity to data providers and software writers, this change will allow the CF checker to check these items. # Status Quo Everyone has work out what the units and standard names of these term should be, and the CF checker has no way of reporting any errors. # Associated pull request PR #305 # Detailed Proposal See PR #305 -- You are receiving this because you are subscribed to this thread. Reply to this email directly or view it on GitHub: https://github.com/cf-convention/cf-conventions/issues/304 This list forwards relevant notifications from Github. It is distinct from [email protected], although if you do nothing, a subscription to the UCAR list will result in a subscription to this list. To unsubscribe from this list only, send a message to [email protected].
