[CF-metadata] 2D latitude, longitude coordinates detection

[John Caron]

Brian Eaton wrote:

>Hi John,
>
>You are correct that the latitude and longitude auxillary coordinate
>variables should be identified by using the coordinates attribute.
>
>The warning that the CF checker should have given is that latitude and
>longitude are multidimensional coordinate variables whose name matches the
>name of one of their dimensions.  We recommended against this in the CF doc
>to avoid the potential confusion with coordinate variables as defined in
>the netCDF User's Guide.  That confusion is manifested in this file's
>metadata as apparently the author expects the latitude and longitude
>variables to be identified as coordinate data since the variable names
>match dimension names.
>
>I believe the checker is correct in saying there are no errors since it can
>only check for syntax errors.  There's no way for it to know that the
>author intended certain variables to have latitude and longitude
>coordinates.  The checker could be improved, however, to give "expert
>analysis" of the metadata.  For example, in addition to reporting syntax
>errors, it could give a summary of the coordinates associated with each
>variable.  A data writer could use this information to verify that his
>intentions were being correctly expressed in the metadata.
>
>Brian
>  
>
Hi Brian:

i thought CF required that there be lat and lon coordinates.  if they 
are missing, isnt that an error?