[CF-metadata] CF Section 5.3 "Reduced Horizontal Grid" and Section 8.2 "compression by gathering" somewhat inconsistent

From: Jonathan Gregory <j.m.gregory>
Date: Tue, 21 Oct 2008 13:56:03 +0100

Dear John and Steve

I may have misunderstood, but I think Ex 5.3 is correct. It is showing how
the data variable PS and the auxiliary coord variables lon and lat, which are
all 2D in principle, may all be compressed by gathering. (As John says, lon and
lat are not 1D in this example.) The uncompressed dimensions londim and latdim
are needed in order to decode the values of rgrid, for scattering back to the
original 2D arrays. The compress attribute indicates that the rgrid variable
is to be treated in this way, just like Sect 8. So I don't think there is a
problem, but perhaps it could be clarified what is going on.

I agree that this scheme doesn't indicate anything about the structure of the
grid, not that it is a Gaussian grid, for instance. I think it was put in to
show how disk space could be saved, that's all.

Best wishes

Jonathan
Received on Tue Oct 21 2008 - 06:56:03 BST