Hi Karl, I'm glad you think the first example makes sense - it's the one that makes most sense to me too! But I'm wondering if one *must* store ap(z)/p0+b(z) (or a(k)+b(k) if that's the parameterisation in use), or if one could store something else and still be a valid CF file? The second example is trying to do two things: 1. Demonstrate one possible example of storing "something else". In this case it's storing "b" in the "z" variable, as shown by the "b: z" entry in the formula terms. (As an aside, I'd find formula terms a whole lot more readable if it allowed commas! e.g. "ap: delta, b: z, ps: surface_pressure" instead of just "ap: delta b: z ps: surface_pressure". There, I've got it off my chest.) 2. Determine whether this is what one *must* store. I strongly suspect/hope not, but would love to know for sure.
Richard Hattersley AVD Iris Technical Lead Met Office FitzRoy Road Exeter Devon EX1 3PB United Kingdom Tel: +44 (0)1392 885702 Fax: +44 (0)1392 885681 Email: [email protected] <mailto:[email protected]> Website: www.metoffice.gov.uk <http://www.metoffice.gov.uk/> ________________________________ From: CF-metadata [mailto:[email protected]] On Behalf Of Karl Taylor Sent: 16 August 2012 17:10 To: [email protected] Subject: Re: [CF-metadata] Dimensionless vertical coordinate values Hi Richard, In your example, I think it would be o.k. to define z(z) as your vertical coordinate variable (your first example). You would then store in z(z) the values of ap(z)/p0+b(z), which is the vertical coordinate as defined in appendix D of the conventions document. I don't think your second example makes sense ... are you storing b in z or ap in z?? I hope someone else will confirm this because I'm not absolutely positive. Best regards, Karl On 8/16/12 5:04 AM, Hattersley, Richard wrote: Hi all, What does the standard name of a dimensionless vertical coordinate imply about the meaning of the numeric values of that coordinate? For example, if a coordinate variable has a standard name of "atmosphere_hybrid_sigma_pressure_coordinate" does that imply it must contain values for either a(k)+b(k) or ap(k)/p0+b(k)? float z(z) ; z:standard_name = "atmosphere_hybrid_sigma_pressure_coordinate" ; z:long_name = "(delta / p0) + sigma" ; z:units = "1" ; z:formula_terms = "ap: delta b: sigma ps: surface_pressure" ; z:positive = "down" ; float delta(z) ; delta:units = "Pa" ; float sigma(z) ; sigma:units = "1" ; float surface_pressure(y, x) ; surface_pressure:units = "Pa" ; Or to put it another way, if it just contained values for ap(k) and appeared in its own list of formula terms would that be invalid? float z(z) ; z:standard_name = "atmosphere_hybrid_sigma_pressure_coordinate" ; z:units = "1" ; z:formula_terms = "ap: delta b: z ps: surface_pressure" ; z:positive = "down" ; float delta(z) ; delta:units = "Pa" ; float surface_pressure(y, x) ; surface_pressure:units = "Pa" ; Richard Hattersley AVD Iris Technical Lead Met Office FitzRoy Road Exeter Devon EX1 3PB United Kingdom Tel: +44 (0)1392 885702 Fax: +44 (0)1392 885681 Email: [email protected] <mailto:[email protected]> Website: www.metoffice.gov.uk <http://www.metoffice.gov.uk>
_______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
