On Mon, Jun 4, 2012 at 2:17 PM, Jonathan Gregory <[email protected]> wrote: > Dear Etienne > > I think the structure you have adopted for the data is fine. > >> double pft(pft) ; >> pft:long_name = "plant functional type" ; >> pft:units = "none" ; >> >> double npp(time, pft, latitude, longitude) ; >> npp:long_name = "npp of carbon for each pft" ; >> npp:units = "kg m-2 year-1" ; > > The specific problem you raise is concerned with the axis attribute. That
Yes, I am mostly concerned with representing the pft axis in a practical manner, it is not a requirement that it adheres strictly to the cf conventions (besides, there are none for this case). > attribute is really intended for identifying spatiotemporal coordinates; > although it may be convenient, it is redundant because they can also be > identified in other ways. It has not been extended for non-spatiotemporal > axes like pft. In your CDL, the pft axis is identified by its long_name. > To make this more reliable, you might want to use a standard_name for this > pft coordinate variable. There isn't such a standard_name at present, but > area_type is often vegetation type in practice, so you could perhaps use > that. We could standardise new area_types by proposals to this email list. The problem with area_type is that it mostly deals with "vegetation types" rather than "plant function types", some models make a distinction between them. For example, a "savanna" vegetation type is made of several "plant function types", such as grass, shrubs and deciduous trees Also currently, area types only has one type for vegetation. > > Also, there is the new proposal, which I expect will go into the > standard_name table, for UN/FAO land cover types, which in many cases are > also vegetation types. > See http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2012/033507.html I will look into that and see if we can adapt our terms to the UN/FAO ones. > > The quantities identified by these standard_names are string-valued, whereas > you expect a numeric pft. However, a string-valued one could be encoded as a > number by using the flag_values and flag_meanings attributes. Numeric values are easier to deal with in many models, and also in displaying (e.g. in grads) > > There is an existing standard name for NPP as well viz > net_primary_productivity_of_carbon (kg m-2 s-1) Thanks, I will see if we can change our names to the CF spec. > > Best wishes > > Jonathan > _______________________________________________ > CF-metadata mailing list > [email protected] > http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata _______________________________________________ CF-metadata mailing list [email protected] http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
