[CF-metadata] How to handle a forecast model with non-monotonic coordinate variables

From: Jonathan Gregory <j.m.gregory>
Date: Tue, 18 Feb 2014 18:08:37 +0000

Dear Jim

> As far as I have ever been able to tell from CF (pre 1.6), there has never been a proscription of missing values in auxiliary coordinates. True coordinate variables (as I think of them) contain definitions of independent axes, which are not acquired data. As a result, it makes no sense for them to have missing values. Auxiliary coordinate variables may very well contain acquired data values, and properly able to have elements marked as missing, independent of whether or not other variables are missing values for the corresponding elements.

_FillValue and missing_value are allowed by Appendix A only for data variables
(D) not coordinate variables (C) in version 1.5 and earlier. In version 1.6
this was clarified and ticket 85 clarifies it further, for version 1.7.

We allow missing data in discrete sampling geometries for elements which don't
correspond to any location i.e. they're just not used at all.

Best wishes

Jonathan
Received on Tue Feb 18 2014 - 11:08:37 GMT