[CF-metadata] axis attribute

[Simon Wood]

Hi Jonathan,

Reading this has made me realize I may have a similar confusion with 
regards to other map projections eg Lambert conformal.  For these should 
the 'axis=X' attribute be attached to the grid x coordinate variable 
(x(x), ie the one we give the standard name 'projection_x_coordinate') 
or the longitude auxiliary coordinate variable (lon(y,x))?  Or should it 
not be used at all in this situation?

regards

Simon Wood


> Thanks for reminding of what I said five years ago! Despite that, I believe
> we produced an inconsistency, so I might change my mind. :-) Isn't it
> inconsistent to
> (a) recommend axis attribute for "generic spatial coords" (with no special
> interpretation, just to provide a hint to the user of data) but
> (b) forbid it with rotated lon and lat?
> I think we should change one of these. Either we should allow X and Y *only*
> with lon and lat, or we should allow them with *any* horizontal axes, but
> stress that if they are not longitude and latitude, they do not carry any
> information except that the data-writer thinks of them as the x and y axes of
> the plot.
> 
>> Allowing axis="X" to denote either the rotated latitude or longitude axes
>> is a recipe for confusion and unlikely to be helpful to any application.
> The help it could be is to suggest it should be plotted as the horizontal axis.
> The confusion it could cause is that some software might be using axis="X" to
> find a longitude axes. Given (a) above, that is not safe, but it is possible
> that assumption has been made.
> 
> I wonder whether any writers of data and applications have any views?
> 
> Cheers
> 
> Jonathan
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-- 
Simon Wood
Meteorology & Remote Sensing, NIWA, NZ	
simon.wood at niwa.co.nz
http://www.niwa.co.nz