[CF-metadata] What do models assume for the shape of the Earth?

[John Caron]

Jonathan Gregory wrote:

>Dear John
>
>  
>
>>Normally I dont see information in the netCDF file on the assumed shape 
>>of the Earth, eg ellipsoidal flattening or even spherical radius. Is 
>>that because it doesnt matter that much? Or is there an assumed standard 
>>that everyone just knows about?
>>    
>>
>
>For climate models it just doesn't matter that much. Models have their own idea
>about the radius of the Earth for calculating grid spacings and so on, but its
>exact value will not make a significant difference to the climate, certainly
>not compared with all the other approximations and unknowns in parameterisation
>schemes. The radius and non-sphericity affect the local g as well, but I guess
>this number is probably separately specified rather than computed by the model.
>Again its precise value is unlikely to be critical.
>  
>
So would everyone agree, that in the absence of explicit information, I 
could use, say, a spherical earth with radius 6370997 m as a reasonable 
default ?