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Re: [cf-satellite] Query related to CF conventions

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  • Subject: Re: [cf-satellite] Query related to CF conventions
  • Date: Fri, 29 Jul 2011 12:07:07 -0600
On 7/29/2011 11:31 AM, Lynnes, Christopher S. (GSFC-6102) wrote:

On Jul 29, 2011, at 8:40 AM, John Caron wrote:


2. CF uses netCDF as its file format.

John,
   How true is this statement?  Our own Global Modeling and Assimilation Office 
claims to be making CF-compliant HDF4 data, and Russ Rew has the following 
statement in the RFC about CF that he submitted to the NASA SPG:

"Because of its simplicity and generality, other file formats can be modeled using 
the CF data model. Thus the concepts and relationships specified in CF may be applied to 
other formats by mapping the variable, dimension, and attribute abstractions in the CF 
data model to analogous concepts in the other formats, in a way that preserves the 
essential characteristics of the data model needed by the CF conventions."

Are we just kidding ourselves if we say we have HDF4 data that is CF-compliant?
--



Hi Chris:
Well, I agree with Russ that "other file formats can be modeled", and its not particularly hard. To make an HDF4/CF mapping robust, you should start a public document that clarifies any issues between the netcdf and hdf4 data model that affects CF. One that I know about is the lack of shared dimensions in HDF4. HDF-EOS got around it in their ODL. One could also use dimension scales (is that what you are doing?), although there may be some things to clarify there. There are likely a cases to document. The issue that Ghansham brought up might be another one.
So id say you arent fooling yourself exactly, but you may not be interoperable with CF-reading software. A public web page that we can link to from our conventions page would likely be the ticket. 

John