2D coordinate variables

John Caron (caron@ucar.edu)
Wed, 14 May 1997 17:37:48 -0600

Hmmm, I was wondering what happened to this group....

Heres a belated comment on the problem of 2d coordinate varibales:

> > I was wondering if there was any way in the netCDF standard to have a 2-d dim-
> > ension grid, ie, N "coordinates" each of which is a lat-lon pair, and then each
> > field is defined on that grid.
> Yes, I did something like this for the UWM/COADS data set (see CDL
> below). The problem is that no software appear able to read it
> directly. In retrospect, I believe it was a mistake, we should have
> adopted something like the COARDS conventions (which I don't whether it
> existed back in 1990).

I dont see anything in COARDS that deals with this. I have the May 1995
doc. Is there something more recent?

> Actually, this idea goes back quite a way.  The concept of "referential
> attributes" was laid out in a report from the NetCDF Users Working
> Group (NUWG) back in 1992.... 

A more obvious generalization of coordinate variables to the 2D case I
think is:

	float mydata(time, lev, lat, lon);

// coordinate system
	float lev(lev);
	float lat(lat, lon);
	float lon(lat, lon);

I would like to hear any arguments against this idea, other than the
obvious that its not (yet) a convention.