[CF-metadata] Two-variable integer Time in CF? (V. Balaji)

From: Jonathan Gregory <j.m.gregory>
Date: Mon, 12 Nov 2007 21:44:16 +0000

Dear Rich

> it seems likely that
> clients will be using some sort of library to achieve
> interoperability with CF time conventions (currently UDUNITS, perhaps
> something else in the near future) and that it would be trivial to add
> to the library handling of the two-variable time case in addition to
> the single variable time

It would make things easier if this were universally the case, but I believe
that a substantial number of users of CF-netCDF read or write the files using
their own programs which call the netCDF library directly, or using generic
utilities which aren't aware of CF or udunits. Hence we have to be careful not
to break things or complicate the convention unnecessarily.

In this case, I think that it would be reasonable to keep the existing udunits-
like convention for time coordinates, and supplement it with an optional
alternative representation in which the component coordinates are stored as
auxiliary coordinate variables (indicated by the coordinate attribute) or
in variables indicated by some other specific convention (analogous to the
formula_terms for vertical coordinates). Extra information can be ignored by
existing applications and will not break them.

Best wishes

Jonathan
Received on Mon Nov 12 2007 - 14:44:16 GMT