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

[John Caron]

Rich Signell wrote:

>
> John,
>
> There are two "sphere" ellipsoids recognized by the EPSG:
>
> Clarke 1866 Authalic Sphere (EPSG_code=7052);  radius=6370997
> GRS 1980 Authalic Sphere (EPSG_code=7048); radius=6371007
>
> Both of these spheres were designed to have the volume of the sphere 
> match the true ellipsoid, and the slight difference of 10 meters 
> represents the progress in understanding the ellipsoid over the 114 
> years!
>
> It sounds like you would like to use the older one, and since it 
> hasn't been specified, we assume it doesn't matter, but...
>
> I would choose the GRS 1980 value, just to "sound" more modern (so 
> that people wouldn't ask me why my netcdf data was based on something 
> that came from 1866)

thanks very much, i will use 6371007 meters.