Hi Jon,
Indeed, the UM global climate model, for example, assumes a spherical
earth.
In the absence of specific datum information I think I would probably
caution against assuming any particular datum is applicable. I can
understand the temptation to use WGS 1984 as a default because it is
widely known and used. However, this implies a degree of accuracy in the
coordinate data which in many instances may well not be justified -
indeed its use might even compound any relative location errors.
As you rightly suggest, if the end-use/application demands a particular
spatial accuracy then any datasets which demonstrably do not not meet
those requirements should probably not be included in the analysis - or
else should be with appropriate caveats, provisos and disclaimers!
Regards,
Phil
> -----Original Message-----
> From: cf-metadata-bounces at cgd.ucar.edu
> [mailto:cf-metadata-bounces at cgd.ucar.edu] On Behalf Of Jonathan Blower
> Sent: 19 April 2010 16:23
> To: Mike Grant
> Cc: cf-metadata at cgd.ucar.edu
> Subject: Re: [CF-metadata] Default datum for latitude and longitude?
>
> Hi Mike,
>
> Yes, that's what I've been doing so far, but I seem to
> remember someone telling me that models tend to be formulated
> on a spherical earth. But maybe if the precise geolocation
> of the model grid points is important (e.g. for small-scale
> models) the datum will always be specified, or a different
> projection used.
>
> Cheers, Jon
>
> -----Original Message-----
> From: Mike Grant [mailto:mggr at pml.ac.uk]
> Sent: 19 April 2010 16:07
> To: Jonathan Blower
> Cc: cf-metadata at cgd.ucar.edu
> Subject: Re: [CF-metadata] Default datum for latitude and longitude?
>
> On 19/04/10 15:43, Jonathan Blower wrote:
> > specification, which datum should be assumed? Spherical Earth?
> WGS84?
>
> If you're picking one at random, I'd go for WGS84 - that's a
> pretty safe bet for a lot of remote sensed and GPS related data.
>
> Cheers,
>
> Mike.
>
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Received on Mon Apr 19 2010 - 09:51:49 BST
