[CF-metadata] axis attribute

From: Jonathan Gregory <j.m.gregory>
Date: Thu, 28 Dec 2006 09:47:48 +0000

Dear John

> >Requirement: A way to identify the horizontal coordinate variables.
> >
> Sorry I dont understand the requirement. Is this for the case where its
> not a lat/lon nor a projection x, y coordinate ? Is the use case
> rotated_latitude_longitude ?

The beginning of the proposal tries to answer that:

Proposal: It can be done using COARDS rules for units in the case of latitude
and longitude. In other cases (such as projection coordinates, rotated latitude
and longitude) the standard name can be used, but that requires recognising
specific names, and standard names are optional anyway.

So, the axis attribute, if present (it is optional), can be used to
identify horizontal coordinates in any case. Lat/lon, projection coordinates,
rotated lat/lon, and any other mapping which might be invented require the
software to recognise specific units or standard names for this purpose. The
axis attribute is a more general solution that works without any knowledge of
the details of the horizontal grid.

> BTW, theres no reference to how rotated_latitude_longitude works in the
> Appendix.

Yes, it is there, under the name "Rotated pole", after "Polar stereographic".

Best wishes

Jonathan
Received on Thu Dec 28 2006 - 02:47:48 GMT