[CF-metadata] WRF staggered grids

From: Jonathan Gregory <j.m.gregory>
Date: Thu, 23 Oct 2003 09:04:48 +0100

Dear John

> Has there been any discusion of staggered coordinate systems?
Yes, informally, but no proposals are "on the table".

> It has variables on various staggerings, for example U is on (z,y,x_stag)
> while V is on (z, y_stag, x), and W is on (z_stag,y,x), where the
> staggered coordinates are the "edges" of the non-staggered coordinates.
>
> On first pass these could constitute seperate coordinate systems, but it
> seems like it would be better to represent how they are related.

I think the representation as separate systems is essential. For most software
that is all which is necessary and the program shouldn't be expected to do
anything cleverer. The issue is whether we want to include additional metadata
which indicates how the systems are related. Are you aware of a need for this
higher-level information? For instance, when would you like to know that the
pressure, U and V are in an Arakawa C-grid arrangement? To record this would
be redundant, in principle, so is it better to deduce it when you need to?

Best wishes

Jonathan
Received on Thu Oct 23 2003 - 02:04:48 BST