Re: [cf-pointobsconvention] Draft 2



Don Murray wrote:
John-

John Caron wrote:

Well, maybe you're right. I notice that CF currently doesnt require
vertical coords. But as a visualizing client, how do you display?
Wouldnt you prefer to insist on something?

No.  We import lots of data point data stored in text files that
only has lat/lon coords.  In the IDV, we plot the data at the
default Z location defined by the user if we don't have a Z dimension.
We don't always want to assume 0 for the Z value.

Just to be clear: this is not about making assumptions about where the z value is (sorry i said that earlier), in fact its the opposite: requiring the data provider to explicitly specify the z position of point data, in order to be CF compliant.

It seems like the possible options are:

1. z coordinate required, with values convertible to height (eg meters), with a vertical datum (reference surface like "mean sea level") specified.
 2. z coordinate required, with values convertible to height (eg meters).
 3. z coordinate required, with values in any vertical coordinate system.
 4. z coordinate required, may be a "nominal" value (just a string description)
 5. No z coordinate required.

I would lean towards 4, but could be convinced of 5 or 3. We should however recommend the data provider add as much info as possible, and make sure there is a standard way to do so.

Could I ask data providers to chime in : how much z info are you willing and able to put in your files?