[CF-metadata] Question on WKT representation of CRS

From: Jonathan Gregory <j.m.gregory>
Date: Thu, 6 Oct 2011 14:25:52 +0100

Dear all

I agree with Seth and Bryan in the point made earlier by Balaji that model
datasets may not truly correspond to any real-world CRS. But for observational
datasets and model datasets where applicable, we should provide the optional
facility to be more precise, as Bruce says.

I think this is opaque:

GEOGCS["WGS 84",
    DATUM["WGS_1984",
        SPHEROID["WGS 84",6378137,298.257223563,
            AUTHORITY["EPSG","7030"]],
        AUTHORITY["EPSG","6326"]],
    PRIMEM["Greenwich",0,
        AUTHORITY["EPSG","8901"]],
    UNIT["degree",0.01745329251994328,
        AUTHORITY["EPSG","9122"]],
    AUTHORITY["EPSG","4326"]]

because the terms it in are not spelled out sufficiently for me to know what
they mean. It is human-readable, indeed, but not self-explanatory. I am very
concerned that we should not import metadata wholesale without being clear
about how it relates to the rest of CF metadata. Hence I would prefer an
incremental addition to the existing facilities of grid_mapping, which I think
is what Eizi suggests. Can we identify some specific extensions which people
need to be made?

The use of EPSG codes would be non-self-describing, but we could provide both
EPSG code and grid_mapping. In that case it would be good to be able to verify
they were consistent. That would require an online EPSG database that could be
used by the CF checker, and some work by someone to establish the
correspondence between EPSG terms and CF metadata.

Best wishes

Jonathan
Received on Thu Oct 06 2011 - 07:25:52 BST