[CF-metadata] examples 5.8, 5.9, and 5.10 in CF Version 1.4

From: Yilmaz Arslanoglu <yilmaz.arslanoglu>
Date: Wed, 8 Jul 2009 12:02:41 +0200

Hi all;

I am sorry if a similar question has already been asked before, but
I could not find in the archive. I am also from computer science field, so
I am quite new to the concepts here :)

My question is, in examples 5.8, 5.9, and 5.10 on pages 27 and 28
in the conventions document version 1.4, we have "lat" and "lon" coordinate
variables, however they are not associated with any units or any other standard
names to enable us identify them neither as latitude nor longitude.
How do we need to identify them in these cases?

As another question if you would not mind:

On page 25 under the title "Horizontal Reference Systems, Grid
Mappings, and Projections",
it says:

"When the coordinate variables for a horizontal grid are not longitude
and latitude, it is
required that the true latitude and longitude coordinates be supplied
via the coordinates attribute.
If in addition it is desired to describe the mapping between the given
coordinate variables and the true
latitude and longitude coordinates, the attribute grid_mapping may be
used to supply this description."

Now, since I have a grid mapping and associated projection parameters,
why should I still need the true latitude
and longitude coordinates be supplied additionally? Can't I perform
the necessary conversion without this information?
That is, isn't it enough to just follow the projection_x_coordinate
and projection_y_coordinate attributes?

Thank you very much,
Yilmaz
Received on Wed Jul 08 2009 - 04:02:41 BST